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Biology, 5th Form > 2. Structures And Functions In Living Organisms > Flashcards

2. Structures And Functions In Living Organisms Flashcards

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1
Q

Chemical elements that are present in carbohydrates :

A

. Carbon
. Hydrogen
. Oxygen

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2
Q

Chemical elements present in proteins :

A

. Carbon
. Hydrogen
. Oxygen
. Nitrogen

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3
Q

Chemical elements present in lipids :

A

. Carbon
. Hydrogen
. Oxygen

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4
Q

How are carbohydrates broken down !?

A

. Carbohydrates are broken down in a chemical reaction, RESPIRATION, to release energy in the form ATP.

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5
Q

What are the smallest units of carbohydrates !?

A

. Simple sugars ( e.g. GLUCOSE and fructose)

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6
Q

complex carbohydrates are made up of…

A

. Many sugar molecules (1000s) that are joined together to make complex carbohydrates such as :
- starch
- glycogen

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7
Q

Why are starch and glycogen better storage molecules !?

A

. Starch and glycogen are better storage molecules as they are LESS SOLUBLE than simple sugars and so have less effect on water movement in and out of cells

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8
Q

What is used to store glucose in plants !?

A

. Starch

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9
Q

What is used to store glucose in animals and fungi !?

A

. Glycogen

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10
Q

lipids or a triglyceride are made up of…

A

3 FATTY ACIDS joined to a GLYCEROL molecule

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11
Q

What are the functions of a lipid !?

A

. Energy storage ( can also be used for fuel in respiration)
. Part of cell membranes
. Thermal insulation
. Electrical insulation - around nerve cells
. Buoyancy

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12
Q

Why may lipids be useful to marine animals !?

A

. Buoyancy - helps marine animals such as whales float

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13
Q

Proteins are made of…

A

. Many AMINO ACIDS joined together

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14
Q

How many different amino acids can be combined to form a protein !?

A

. There are 20 different amino acids which can be combined in any order, resulting in millions of different protein structures

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15
Q

Why is the shape of a protein important !?

A

. As the shape of a protein helps it to carry out its job

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16
Q

Functions of protein in the body :

A

. growth and repair of cells and tissues
. fuel for respiration
. Controlling chemical reactions- these are enzymes
. Messenger molecules- hormones
. Combating disease- antibodies
. Transport- e.g. haemoglobin and cell membrane proteins

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17
Q

TEST FOR GLUCOSE :

A

. Benedict’s solution :
1. Add Benedict’s solution to a sample of food ( in solution )
2. Place in a water bath at 80*c for 5 minutes
3. If glucose is present the colour will change from blue to brick red. If it’s green, yellow or orange it’s still a positive result but will have a lower concentration of the sugar.🟦➡️🟥

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18
Q

TEST FOR STARCH :

A

. Iodine test :
1. Add a few drops or orange iodine solution to the sample on a spotting tile.
2. A blue-black colour indicates the presence of starch🟧➡️🟦⬛️

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19
Q

TEST FOR PROTEIN :

A

. Biuret :
1. Add 2 cm*3 water to a food sample and shake (if not already liquid)
2. Add an equal volume of dilute potassium hydroxide and shake
3. Add two drops of 1% copper sulphate solution
4. If protein is present then a pale purple colour will develop 🟦➡️🟪

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20
Q

TEST FOR LIPIDS :

A

. Emulsion :
1. The food sample is placed in a test tube
2. Add a small volume of absolute ethanol and shake to dissolve any lipid in the alcohol
3. Add an equal volume of water
4. A cloudy white colour ( caused by an emulsion forming) indicates the presence of a lipid ⬜️

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21
Q

What is the role of an enzyme in a metabolic reaction !?

A

. An enzyme is a biological CATALYST which is a chemical that increases the rate of (a metabolic) reaction without being used up itself

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22
Q

How does temperature affect the rate of an enzyme controlled reaction !?

A

. As temperature increase the enzyme and substrate have more KINETIC ENERGY. They move faster so there are more successful collisions
. All proteins are held together by forces between different parts of the amino acid chain. HIGH TEMPERATURES disrupt these forces, so the shape changes

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23
Q

What is the meaning of a,“denatured enzyme (or protein).”

A

. When we say a protein is DENATURED it means that (in enzymes) the active site has changed shape so it can no longer bind with the substrate meaning an enzyme-substrate complex can no longer be formed.

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24
Q

How does temperature changes affect enzyme functions !?

A

. As temperature increases so does the rate of reaction - this occurs until optimum temperature is reached
. Above optimum temperature the heat breaks the forces holding proteins in the correct shape. The ACTIVE SITE CHANGES SHAPE so it is no longer complimentary with the substrate. The SUBSTRATE CAN NO LONGER BIND, so the reaction cannot occur.
. The enzyme has been DENATURED

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25
Q

Why does an increase in temperature affect the rate of reaction !?

A

. This is because the higher temperature gives the enzymes and substrates MORE KINETIC ENERGY. They move faster and COLLIDE MORE OFTEN, so you get more reactions per second.

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26
Q

Practical: investigating the EFFECT OF TEMPERATURE ON ENZYMES:

A

. You can use any enzyme to investigate the effect of temperature, this experiment studies the effect temperature has on AMYLASE
. Amylase digests starch.
- mix 10cm3 of 10% starch suspension and 5cm3 of 5% amylase in a boiling tube and heat in a water bath.
- every minute take one drop of this mixture and add it to one drop of iodine solution in the spotting tile.
- when digestion is complete and no starch is present, iodine will stay orange 🟧 (rather than turning blue black🟦⬛️)
- repeat using different water bath temperatures

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27
Q

How does a change in pH affect the rate of reaction !?

A

. The pH inside cells is neutral (pH 7) and most enzymes work best at this pH. Others work at different pH values in specialised parts of the body.
. If the PH of the environment CHANGES it can affect the shape of the enzyme. The ACTIVE SITE CHANGES SHAPE so it is no longer complementary to the substrate. The enzyme is DENATURED and the reaction can no longer occur.

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28
Q

Practical: investigating the EFFECT OF PH ON ENZYMES

A

. You can use any enzyme to investigate the effect of pH
. Potato contains the enzyme catalase which breaks down hydrogen peroxide, forming water and oxygen gas.
-Add 10 potato disks (1cm thick, cut with a cork borer) to 20cm*3 catalase and measure the volume of gas produced in 5 minutes
-the pH can be altered by adding different volumes of a weak alkali (e.g. sodium carbonate) or a weak acid (e.g. ethanoic acid) - use universal indicator paper to determine the pH of the solution each time

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29
Q

Examples of organisms that respire AEROBICALLY:

A

. All animals and plants

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30
Q

Word equation for AEROBIC respiration:

A

Glucose + oxygen➡️Carbon dioxide + water

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31
Q

ATP provides cells with…

A

. ATP provides cells with ENERGY

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32
Q

Respiration without oxygen is called…

A

. ANAEROBIC Respiration

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33
Q

Why might ANAEROBIC respiration be useful in food production !?

A

. As we use fungi such as yeast in bread and alcohol production. In both processes, we supply glucose and keep the yeast in low oxygen conditions so the cells can respire anaerobically. The carbon dioxide produced forms bubbles in bread dough and the ethanol provides the alcohol content in beer and wine.

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34
Q

Practical: INVESTIGATING RESPIRATION - (germinating peas) -

A

. When investigating respiration we want to show that only living things respire.
. To do this we use a CONTROL experiment.- identical to original without the independent variable
- GERMINATING PEAS:
As the peas start to grow they respire, releasing heat. The thermos flask is insulated, so heat isn’t transferred to the surroundings and we can measure the change in temperature.
We only see a temperature rise in thermos A, as the peas in thermos B are dead.
In both thermos flasks the peas are soaked in Milton Solution (bleach). This kills any bacteria

We could also use gas delivery tubes to collect any gas produced. The gas can then be BUBBLES THROUGH LIMEWATER. The gas from flask A only would turn the limewater CLOUDY - this shows that CARBON DIOXIDE IS PRODUCED

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35
Q

Practical: INVESTIGATING RESPIRATION - (hydrogen carbonate indicator and insects) -

A

. HYDROGEN CARBONATE INDICATOR AND INSECTS:
- this indicator is red, but turns yellow when carbon dioxide concentration increases.
- carbon dioxide reacts with water to form a weak acid

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36
Q

Equipment : INVESTIGATING RESPIRATION - (germinating peas) -

A

. Thermos flasks x2
. Thermometers x2
. Cotton wool plugs x2
. Peas seed in Milton solution
. DEAD pea seed in Milton solution

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37
Q

Equipment : INVESTIGATING RESPIRATION - (hydrogen carbonate indicator and insects) -

A

. Test tubes x2
. Tightly fitting bung x2
. Hydrogen carbonate indicator
. Insect
. Support

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38
Q

What is the excretory product of the LUNGS !?

A

. Carbon Dioxide

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39
Q

Where is Carbon dioxide made !?

A

. In Respiring cells

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40
Q

How is Carbon dioxide made !?

A

. Respiration

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41
Q

Where is Carbon dioxide removed !?

A

. Lungs via blood plasma

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42
Q

What is the excretory product of the KIDNEYS!?

A

. Urea

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43
Q

Where is Urea made !?

A

. Liver cells

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44
Q

How is Urea made!?

A

. Via the breakdown of amino acids

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45
Q

Where is Urea removed !?

A

. Kidneys + skin

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46
Q

What is Excretory product of the SKIN!?

A

. Urea

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47
Q

What is the role of a Nephron !?

A

. They are structures that filter blood

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48
Q

How many Nephrons does a kidney contain !?

A

. Millions

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49
Q

What is the role of the KIDNEY !?

A

. The kidney filters the blood and removes any excess materials and passes them onto the bladder to be excreted

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50
Q

What are the three main sections of the kidney !?

A

. Cortex (around the outside, lighter colour)

. Medulla (middle, triangle shaped)

. Pelvis (centre, yellowy🟨)

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51
Q

What function does the nephron carry out !?

A

. Ultrafiltration

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52
Q

STAGE 1- ULTRAFILTRATION: (gap fill)

  1. The diameter of the ________ _________ at the exit of the __________ is smaller than the diameter of the ________ _________at the entrance. This creates a build-up of pressure in the capillaries forming the glomerulus.
A

. The diameter of the [EFFERENT ARTERIOLE] at the exit of the [GLOMERULUS] is smaller than the diameter of the [AFFERENT ARTERIOLE] at the entrance. This creates a build-up of pressure in the capillaries forming the glomerulus.

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53
Q

STAGE 1- ULTRAFILTRATION: (gap fill)

  1. This pressure forces _____ molecules such as ____, _______, _____ _____ and salts out of the capillaries of the __________ and into the ______’_ _______. This forms the __________ _______
A

. This pressure forces SMALL molecules such as UREA, GLUCOSE, AMINO ACIDS and salts out of the capillaries of the GLOMERULUS and into the BOWMAN’S CAPSULE. This forms the GLOMERULAR FILTRATE

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54
Q

STAGE 1- ULTRAFILTRATION: (gap fill)
3. Larger molecules like ________ or ___ _____ _____ are ___ ___ to fit across the capillary walls and therefore stay in the _____

A

. Larger molecules like PROTEINS or RED BLOOD CELLS are TOO BIG to fit across the capillary walls and therefore stay in the BLOOD

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55
Q

What controls which molecules can pass into the bowman’s capsule !?

A

. The BASEMENT MEMBRANE surrounding the capillaries controls which molecules can pass onto the bowman’s capsule

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56
Q

What feature of the capillaries of the glomerulus helps with the process of ULTRAFILTRATION!?

A

. The capillaries of the glomerulus have gaps between the cells

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57
Q

STAGE 2 - SELECTIVE REABSORPTION: (gap fill)
1. The filtrate travels to the ________ __________ _______ (___). However it contains a lot of useful materials such as _______ which would be wasted unless they were recovered

A

. The filtrate travels to the PROXIMAL CONVOLUTED TUBULE (PCT). However it contains a lot of useful materials such as GLUCOSE which would be wasted unless they were recovered

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58
Q

STAGE 2 - SELECTIVE REABSORPTION: (gap fill)
2. There are ___________ cells within the walls of the ___. These move the useful materials back into the _____ ______. Initially molecules will move by _________, but some substances are also moved against a concentration gradient using ___. This is called ______ _________.

A

. There are SPECIALISED cells within the walls of the PCT. These move the useful materials back into the BLOOD STREAM. Initially molecules will move by DIFFUSION, but some substances are also moved against a concentration gradient using ATP. This is called ACTIVE TRANSPORT.

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59
Q

What is reabsorbed during selective reabsorption !?

A

. ALL of the glucose and amino acids are reabsorbed along with some salts and 80% of the water

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60
Q

How are the cells lining the PCT specialized for movement of molecules!?

A

. They have a FOLDED MEMBRANE to increase surface area

. They have MANY MITOCHONDRIA to provide ATP for active transport

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61
Q

STAGE 3 - WATER REABSORPTION:
Where is the majority of your water reabsorbed !?

A

. 80% of water is reabsorbed in the PCT

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62
Q

STAGE 3 - WATER REABSORPTION:
What role does the LOOP OF HENLE play in water reabsorption!?

A

. The loop of Henle concentrates the urine by transporting salt into the blood by ACTIVE TRANSPORT. This causes water to diffuse into the blood by OSMOSIS

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63
Q

Why might urine be a darker colour !?

A

. If you have lost a lot of water through sweating or perhaps haven’t taken in any your body will try to reabsorb as much water from the filtrate as it can. This makes the urine very concentrated, lower vol. of water so darker colour.

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64
Q

What is OSMOREGULATION !?

A

. Osmoregulation is when the COLLECTING DUCT responds to the hormone ADH to vary how much water is reabsorbed

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65
Q

Put these in the correct order:
. Ureter
. Bladder
. Urethra
. Kidney

A

Kidney➡️Ureter➡️Bladder➡️Urethra

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66
Q

What main three things make up urine !?

A

. Water
. Urea
. Ions

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67
Q

Are organisms able to respond to changes in their environment!?

A

. Organisms are able to respond to changes in their environment and make a coordinated response

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68
Q

How do Humans and other Animals make CO ORDINATED responses !?

A

. Animals and Humans have two organ systems to do this:
- the nervous system
- the endocrine system

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69
Q

Are plants able to respond to changes in their environment!?

A

. Yes, for example they can respond to the direction of light and grow towards it (phototropism) etc.

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70
Q

What three things does a CO-ORDINATED response need !?

A

. A stimulus

. A receptor

. An effector

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71
Q

How is the link between the stimulus and the response made !?

A

. The link is made by the nervous (and) or the endocrine system

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72
Q

What is the CENTRAL NERVOUS SYSTEM made up Of!?

A

. The CNS consists of the brain and the spinal chord
- and is linked to sense organs by nerves

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73
Q

What is the function of the CNS !?

A

. The CNS coordinates all of the nervous responses such as moving or reflexes

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74
Q

What is the PERIPHERAL nervous system!?

A

. The peripheral nervous system contains all of the other nerves which send impulses to all the effectors

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75
Q

What is the Definition of HOMEOSTASIS!?

A

. Homeostasis is the maintenance of a constant internal environment

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76
Q

Examples of homeostasis:

A

. Body water content

. Body temperature

. Blood sugar level

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77
Q

How does HORMONAL communication control responses !?

A

. The ENDOCRINE systems uses proteins, called HORMONES, that are released into the blood stream by GLANDS and target specific cells in the body

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78
Q

How does NERVOUS communication control responses !?

A

. IMPULSES from receptors pass along SENSORY NEURONES until they reach the brain and spinal chord (CENTRAL NERVOUS SYSTEM). Impulses pass to RELAY NEURONES in the CNS. The impulse is then passed to effectors (muscles or glands) along MOTOR NEURONES

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79
Q

How fast is the ENDOCRINE system !?

A

. Slow (except adrenaline)

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80
Q

What type of message does the ENDOCRINE system send !?

A

. Chemical message

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81
Q

How does the ENDOCRINE system relay messages !?

A

. Via the blood- dissolved in the plasma

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82
Q

What is the response to the message sent from the ENDOCRINE System!?

A

. only target cells respond even though the message is sent all over the body

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83
Q

What is the role of the ENDOCRINE system in the body !?

A

. It controls long term processes such as reproduction and growth

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84
Q

How fast is the NERVOUS system!?

A

. Rapid

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85
Q

What type of message does the NERVOUS system send !?

A

. Electrical impulses

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86
Q

How does the NERVOUS system relay its messages!?

A

. Along neurones

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87
Q

What is the response the the message sent by the NERVOUS system !?

A

. The message is sent directly to a muscle or a gland- not all over the body

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88
Q

What is the role of the NERVOUS system in the body !?

A

. Used when a fast response is needed

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89
Q

What is the role of NEUROTRANSMITTERS at synapses !?

A

. An electrical impulse travels along an axon

. This triggers the nerve-ending of a neutron to release CHEMICAL MESSENGERS called neurotransmitters

. These chemicals DIFFUSE across the synapse and bind with receptor molecules on the membrane of the next neuron

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90
Q

What is a synapse!?

A

. Two neurones do not make direct contact. Where they meet, there is a very small gap called a synapse

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91
Q

What are reflex actions !?

A

. Reflex actions are AUTOMATED actions which DO NOT involve the BRAIN

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92
Q

Are reflex actions fast !?

A

. They are very fast actions

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93
Q

What is involved in a reflex action !?

A

. Sensory neurone

. Relay neurone

. Motor neurone

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94
Q

The movement of an impulse from receptor to effector is called…

A

. … A reflex arc

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95
Q

What is the Role of RECEPTOR when withdrawing your finger from a hot object!?

A

. The receptors detect the STIMULUS (change in temperature) and send an IMPULSE along the SENSORY NEURONE

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96
Q

What is the role of the SENSORY neurone when withdrawing your finger from a hot object !?

A

. The sensory neurone passes the impulse to the SPINAL CHORD to a RELAY neurone. ( the gaps between neurones is called a synapse)

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97
Q

What is the role of the RELAY neurone when withdrawing your finger from a hot object !?

A

. The relay neurone passes the impulse through the spinal chord to a MOTOR NEURONE

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98
Q

What is the role of the MOTOR neurone when withdrawing your finger from a hot object !?

A

. The motor neurone causes the effector (in this case arm muscles) to contract and move the arm away from the STIMULUS (hot object)

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99
Q

What is the function of an eye, (as a receptor)!?

A

. The eye is a SENSORY organ which detects light and sends an IMPULSE to the brain which converts that information into an image which is what you “see”.

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100
Q

What is the CORNEA and what is it’s job!?

A

. The cornea is a curved transparent disc at the front of the eye. Does most of the focusing

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101
Q

What is the PUPIL?!

A

. A circular opening who’s size is controlled by the iris (the coloured part of the eye)

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102
Q

What is the IRIS and what is it’s job ?!

A

. A ring of muscles with a hole in the middle (pupil). The iris controls how much light enters the eye

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103
Q

What is the LENS and what is it’s job!?

A

. The lens is soft, flexible and transparent. It’s shape can be changed to fine tune the focusing of light onto the retina

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104
Q

What are the CILIARY MUSCLES and what is their job !?

A

. A ring of muscles at the edge of the eye which circles the lens. When is contracts the lens gets fatter. When it relaxes the lens gets thinner

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105
Q

What are SUSPENSORY LIGAMENTS and what is their job!?

A

. Strong fibres which attach the lens to the ciliary miscle

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106
Q

What does the RETINA contain !?

A

. Contains light sensitive cells called rods and cones

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107
Q

What does the OPTIC NERVE consist of and what is it’s job!?

A

. Consists of many neurones which carry impulses from the retina to the brain

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108
Q

What is the FOVEA !?

A

. The region of the retina with the greatest number of cones

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109
Q

What is the CONJUNCTIVA and what’s its job !?

A

. A mucous membrane that covers the eye to prevent infection

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110
Q

Why is the eye a good receptor organ !?

A

. The eye is a sense organ containing receptors sensitive to light intensity and colour

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111
Q

What happens to the eye when in dim light !?

A

. In dim light the RADIAL MUSCLES CONTRACT and circular muscles relax. This makes the iris narrower and the PUPIL DILATES

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112
Q

What happens to the eye when in bright light !?

A

. In Bright light the CIRCULAR MUSCLES CONTRACT and radial muscles relax. This makes the iris wider and the PUPIL CONSTRICTS

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113
Q

An example of a REFLEX ARC:

A

. Iris reflex etc……

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114
Q

The changes that take place in the eye which allow us to see objects at DIFFERENT DISTANCES are called…

A

. …accommodation

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115
Q

When focusing on an object FAR AWAY light rays entering the eye are parallel or diverging !?

A

. Almost parallel when they reach the cornea so the lens does not need to refract them much to focus light on the retina

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116
Q

When focusing on an object CLOSE UP are light rays entering the eye parallel or diverging !?

A

. Light rays entering the eye are diverging so the lens needs to refract the light to ensure it focusses onto the retina

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117
Q

When focusing on an object FAR AWAY what happens to the CILIARY MUSCLES !?

A

. When focusing on an object far away ciliary muscles RELAX

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118
Q

When focusing on an object FAR AWAY are the SUSPENSORY LIGAMENTS tight of slack !?

A

. When focusing on an object far away due to the ciliary muscles being relaxed the suspensory ligaments are pulled tight

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119
Q

When focusing on an object FAR AWAY what happens to the lens !?

A

. When focusing on an object far away the lens is pulled thin and has a less convex shape

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120
Q

When focusing on an object CLOSE UP what happens to the CILIARY MUSCLES !?

A

. When focusing on an object Close up ciliary muscles contract

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121
Q

When focusing on an object CLOSE UP are the SUSPENSORY LIGAMENTS tight or slack !?

A

.When focusing on an object close up dues to the contracting ciliary muscles the suspensory ligaments are slack

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122
Q

When focusing on an object CLOSE UP what happens to the LENS !?

A

. When focusing on an object close up Lens is not stretched out so becomes thicker with a more convex shape

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123
Q

Is there a lot of light refraction when focusing on an object FAR AWAY !?

A

. As the lens is less convex there is LESS REFRACTION of light

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124
Q

Is there a lot of light refraction when focusing on an object CLOSE UP!?

A

. As the lens is more convex there is more refraction of light

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125
Q

Why when the environment gets TOO COLD do or hairs stand on end !?

A

. The hair traps a layer of wait which, like a seals blubber provides INSULATION for conduction of heat

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126
Q

Why when does the environment get TOO COLD do we sweat less !?

A

. Less sweat is released therefore less heat is lost via evaporation

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127
Q

What is VASOCONSTRICTION !?

A

. Vasoconstriction is when Arterioles supplying the capillaries near the surface of the skin get NARROWER -they CONSTRICT. LESS blood will flow through the capillaries near the surface of the skin, therefore LESS heat will be lost by RADIATION

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128
Q

What is VASODILATION!?

A

. Vasodilation is when Arterioles supplying the capillaries near the surface of the skin get WIDER -they DILATE. MORE blood will flow through the capillaries near the surface of the skin, therefore MORE heat will be lost by RADIATION

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129
Q

How does our skin react when the environment gets TOO COLD !?

A

. Hairs stand on end

. Less sweat released

. Vasoconstriction

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130
Q

How does out skin react when the environment is TOO HOT !?

A

. Hairs lie flat

. More sweat is released

. Vasodilation

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131
Q

Why do the hairs on our skin lie flat when the environment is TOO HOT!?

A

. Hairs lie flat and therefore and insulating layer of air is not formed

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132
Q

Why do we sweat more when the environment is TOO HOT !?

A

. Sweat ISN’T cold - the sweat is secreted at NORMAL BODY TEMPERATURE. When the sweat EVAPORATES, heat energy is taken away from the skin as EVAPORATION OF WATER REQUIRES ENERGY

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133
Q

What gland secretes ADRENALINE!?

A

. Adrenal gland

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134
Q

What gland secretes INSULIN!?

A

. Pancreas

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135
Q

What gland secretes TESTOSTERONE!?

A

. Testes

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136
Q

What gland secretes PROGESTERONE!?

A

. Ovaries

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137
Q

What gland secretes OESTROGEN!?

A

. Ovaries

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138
Q

What gland secretes ADH !?

A

. Pituitary gland

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139
Q

What gland secretes FSH!?

A

. Pituitary gland

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140
Q

What gland secretes LH!?

A

. Pituitary gland

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141
Q

What is the FUNCTION of ADRENALINE !?

A

. Increases heart rate and breathing rate for fight, fright or flight

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142
Q

What is the FUNCTION of INSULIN!?

A

. Causes liver and muscles to take up glucose and convert it to glycogen for storage

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143
Q

What is the FUNCTION of TESTOSTERONE!?

A

. Stimulates development of male secondary sexual characteristics

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144
Q

What is the FUNCTION of PROGESTERONE !?

A

. Maintains uterus lining and controls the development of secondary female characteristics

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145
Q

What is the FUNCTION of OESTROGEN!?

A

. Stimulates uterus lining to develop and the development of secondary female characteristics

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146
Q

What is the FUNCTION of ADH!?

A

. Reduces the amount of water lost in urine

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147
Q

What is the FUNCTION of FSH !?

A

. Stimulates an egg to mature in the ovary

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148
Q

What is the FUNCTION of LH!?

A

. Stimulates the release of an egg from the ovary (ovulation)

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149
Q

Is a cell big or small ?

A

. A cell is the smallest possible unit of life

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150
Q

What is the role of an organelle !?

A

. Organelles are small structures which carry out jobs needed to keep the cell alive

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151
Q

What does a plant cell contain the animal cells do not !?

A

. Chloroplasts
. Vacuole
. Cell wall

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152
Q

Function of a NUCLEUS !?

A

. Controls the activity of the cell ( by making proteins)
. Controls the CHROMOSOMES

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153
Q

What is a chromosome!?

A

. Strands of DNA 🧬 which carry the genes (each gene codes for a protein)

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154
Q

Function of the CELL MEMBRANE!?

A

. Boundary between the cytoplasm and the cell’s surroundings. Controls what substances enter and leave the cell (selectively permeable)

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155
Q

Function of the CYTOPLASM!?

A

. Jelly-like liquid where CHEMICAL reactions occur

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156
Q

Function of the MITOCHONDRIA!?

A

. Carries out some reactions of AEROBIC RESPIRATION, producing ATP

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157
Q

What is ATP !?

A

. An energy carrier molecule

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158
Q

Function of the RIBOSOMES!?

A

. Synthesise (assemble) proteins from amino acids

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159
Q

Function of CHLOROPLASTS!?

A

. Absorb light energy and use it to carry out the chemical reactions of PHOTOSYNTHESIS, making biological molecules for plant cells

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160
Q

Function of the CELL WALL!?

A

. Made of CELLULOSE (a carbohydrate) in plants. Helps to keep plant cells in a fixed shape (keeping the plant upright)

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161
Q

Function of the VACUOLE!?

A

. Filled with a watery liquid called CELL SAP; stores dissolved sugars, mineral ions and other substances

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162
Q

Definition of DIFFUSION !?

A

. Diffusion is the random movement of particles from an area of high concentration to an area of lower concentration

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163
Q

How does TEMPERATURE affect the rate of DIFFUSION !?

A

. At higher temperatures, molecules have more kinetic energy and so move faster. Therefore diffusion occurs faster

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164
Q

How does CONCENTRATION GRADIENT affect the rate of DIFFUSION!?

A

. If there is a very large difference in concentration between two areas, molecules will diffuse from the higher to the lower concentration quickly. If the concentration gradient is small, diffusion will happen more slowly

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165
Q

How does DISTANCE affect the rate of DIFFUSION !?

A

. Diffusion takes longer if the molecules have to travel further (molecules don’t travel in a straight line). Therefore cells are small (smaller volume decreases distance)

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166
Q

How does SURFACE AREA : VOLUME affect the rate of DIFFUSION!?

A

. A larger surface area speeds up the rate of diffusion as there are more opportunities for the molecules to move , which is why surfaces such as alveoli in the lungs are so large

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167
Q

How does SURFACE AREA TO VOLUME RATIO affect the rate of DIFFUSION !?

A

. This is more significant, as the two counteract each other: an efficient exchange surface has a surface area which is very large compared to the distance the molecules must travel

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168
Q

What happens to SA:V When structures are small !?

A

. SA :V is increased when structures are small

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169
Q

Definition of OSMOSIS!?

A

. Osmosis is the net diffusion of free water molecules from an area of high water concentration to an area of low water concentration across a partially permeable membrane

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170
Q

What are free water molecules !?

A

. free water molecules are what we describe as water molecules whose movement is not restricted by their environment

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171
Q

What is a partially permeable membrane !?

A

. A partially permeable membrane is a membrane that only allows certain particles through

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172
Q

What is ‘water potential’ !?

A

. water potential is a measure of the concentration of free water molecules in a solution

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173
Q

What is the water potential of pure water!?

A

. Pure water has a water potential of zero

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174
Q

What happens to the water potential of pure water as solute is added !?

A

. As solute is added, water potential falls as there will be a lower concentration of free water molecules.

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175
Q

What is the water potential of concentrated solutions!?

A

. Concentrated solutions have a very LOW water potential.

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176
Q

In osmosis, which direction does water move (HWP, LWP) !?

A

. In osmosis, water moves from an area of high water potential to an area of lower water potential

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177
Q

What is an isotonic solution ?

A

. The solution outside the cell has the same water potential as in the cell

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178
Q

What is a hypotonic solution ?

A

. The solution outside the cell has a higher water potential then inside the cell

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179
Q

What is a hypertonic solution ?

A

. The solution outside the cell has a lower water potential then inside the cell

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180
Q

What is the movement of free water molecules in an ISOTONIC SOLUTION !?

A

. No net movement

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181
Q

What is the movement of free water molecules in a HYPOTONIC SOLUTION !?

A

. Net movement of free water molecules into the cell

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182
Q

What is the movement of free water molecules in a HYPERTONIC SOLUTION !?

A

. Net movement of free water molecules out of the cell

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183
Q

What happens to ANIMAL cells in hypotonic solutions !?

A

. They become LYSED

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184
Q

What happens to ANIMAL cells in isotonic solutions !?

A

. They are normal

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185
Q

What happens to ANIMAL cells in hypertonic solutions !?

A

. They become shrivelled

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186
Q

What happens to PLANT cells in hypotonic solutions !?

A

. They are Turgid (normal)

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187
Q

What happens to PLANT cells in Isotonic solutions !?

A

. They are flaccid

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188
Q

What happens to PLANT cells in hypertonic solutions !?

A

. They become plasmolyzed
(plant wilts)

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189
Q

Definition of ACTIVE TRANSPORT !?

A

. Active transport is the movement of molecules from an area of low concentration to an area of high concentration using ATP

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190
Q

Examples of active transport!?

A

. Glucose is absorbed by active transport in the small intestine
. Plants use in RHC to absorb mineral ions

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191
Q

Why does active transport require ATP !?

A

. As it is used by organisms to transport substances AGAINST the concentration gradient
( using carrier proteins )

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192
Q

practical: investigate the impact SA:V has on the rate of diffusion - (living)

A

. Use agar cubes of different sizes
- the cubes contain an alkali and an indicator (they are placed in acid)
- as the acid diffuses into the cube it reacts with the alkali - turning the indicator colourless

(Smallest cube becomes colourless fastest)

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193
Q

practical: investigate the impact concentration gradient has on the rate of osmosis- (living)

A

. Potato chips can be placed in sucrose or salt solutions of different concentrations
- osmosis will occur until the water potential of the tissue and the solution are the same; (this causes a mass change)
- LEAVE FOR 20 MINS

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194
Q

practical: investigate the impact concentration gradient has on the rate of osmosis- (HIGH WATER CONCENTRATION)

A

. If the solution has a higher water concentration , water will move into the potato chip and the mass will increase

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195
Q

practical: investigate the impact concentration gradient has on the rate of osmosis- (LOW WATER CONCENTRATION)

A

. If the solution has a lower water concentration, water will move out of the potato chip and the mass will decrease

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196
Q

practical: investigate the impact concentration gradient has on the rate of osmosis- (non- living)

A

. Visking tubing ( only allows small soluble molecules to pass through )
- e.g. glucose and water

. You could change the concentration of the sucrose solution - the height the liquid rises in a set time will increase if osmosis is faster

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197
Q

practical: investigate the impact temperature has on the rate of osmosis- (non living)

A

. Visking tubing ( only allows small soluble molecules to pass through )
- e.g. glucose and water

. You could change the temperature of the water - the height the liquid rises in a set time will increase if osmosis is faster

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198
Q

practical: investigate the impact concentration gradient has on the rate of osmosis- (living)

A

. Use thin sections of onion cells
- TURGID- soaked in pure water
- PLASMOLYSED- soaked in a concentrated salt solution

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199
Q

What happens in the process of Photosynthesis

A

. Plants use the simple molecules CARBON DIOXIDE and WATER to make GLUCOSE and OXYGEN
(Using light energy)

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200
Q

How do plants 🌱 obtain LIGHT ENERGY needed for Photosynthesis!?

A

. It is absorbed by the chlorophyll in their chloroplasts

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201
Q

How does photosynthesis aid the plant with respiration!?

A

. Photosynthesis converts light energy into stores chemical energy which can be used by the organism for respiration

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202
Q

What are the three factors affecting the rate of photosynthesis!?

A
  1. The availability of the substrates for the reaction by - carbon dioxide and water

2.The energy available to allow the reaction to occur - light intensity

  1. The kinetic energy available to move substrate and enzyme molecules - increasing the temperature
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203
Q

What happens when you add more carbon dioxide to investigate its affect on the rate of photosynthesis!?

A

. By adding more carbon dioxide the reaction can happen faster, as there are more molecules to collide with the enzymes. However, we reach a point when adding more carbon dioxide has no effect - There is a lack of energy.

204
Q

What happens when you add more energy to investigate its affect on the rate of photosynthesis!?

A

. By adding a bright light we increase the rate of photosynthesis, as there is more energy for the reaction to occur. This doesn’t last forever as at high light
Intensity is a different factor is limiting
(and so the graph levels off).

205
Q

What happens when you add more kinetic energy to investigate its affect on the rate of photosynthesis!?

A

Increasing temperature speeds up the reaction. This is because the enzymes and substrates have more kinetic energy and collide more often. However, at high temperatures the rate of photosynthesis decreases and the reaction stops. This is because the enzymes carrying out the stages of photosynthesis have been denatured.

206
Q

practical: investigate photosynthesis, showing the evolution of oxygen from a water plant
- (APPARATUS)

A

. Beaker
. Water plant
. Funnel
. Boiling tube
. Splint
. Bunsen burner
. Heatproof mat

207
Q

practical: investigate photosynthesis, showing the evolution of oxygen from a water plant
- (METHOD)

A

. Take a bundle of shoots of the water plant
. Submerge them in a beaker of water underneath an upturned funnel
. Fill a boiling tube with water and place it over the end of the funnel
. As oxygen is produced, the bubbles of gas will collect in the boiling tube and displace the water.

208
Q

How to test for oxygen !?

A

. Relight a glowing splint

209
Q

practical: investigate light + photosynthesis

A

. A Length of pond weed (ELODEA) is put in a beaker of water and the number of bubbles released from the stalk in one minute is counted. The distance of a bench lamp can we move to vary the light intensity,or differing masses of sodium bicarbonate to vary the carbon dioxide concentration.

210
Q

What are nutrients!?

A

. They are biological molecules which are required by the body

211
Q

Source of carbohydrates!?

A

. Bread
. Rice
. Potatoes

212
Q

Source of protein!?

A

. Meat
. Eggs
. Fish
. Quinoa

213
Q

Source of lipids !?

A

. Butter
. Avocados
. Cream

214
Q

What is the function of carbohydrates!?

A

. Fuel for respiration

215
Q

What is the function of proteins!?

A

. Growth and repair of cells and tissues
. Fuel for respiration

216
Q

What is the function of lipids!?

A

. Store of energy
. Thermal and electrical insulation
. Fuel for respiration

217
Q

Source of iron !?

A

. Red meat
. Spinach
. Liver

218
Q

Source of calcium!?

A

. Milk and dairy products
. Fish
. Fresh veg

219
Q

What is the function of iron!?

A

. Forms part of the haemoglobin which binds to oxygen

220
Q

What is the function of calcium !?

A

. Needed to form bones and teeth

221
Q

What is the deficiency disease you can obtain if lacking iron !?

A

. Anaemia

222
Q

What is the deficiency disease that you could obtain if lacking calcium !?

A

. Rickets

223
Q

What is a source of vitamin A !?

A

. Fish liver oil
. Butter
. Carrots

224
Q

What is a source of vitamin C !?

A

. Fresh fruit and vegetables

225
Q

What is a source of vitamin D !?

A

. Dairy products
. Oily fish

226
Q

What is the use of vitamin A in the body !?

A

. Making a chemical in the retina and also protects the surface of the Eye

227
Q

What is the use of vitamin C in the body !?

A

. Needed for cells and tissues to stick together

228
Q

What is the use of vitamin D in the body !?

A

. Needed to absorb calcium and phosphate ions from food

229
Q

What is the effect of vitamin A deficiency!?

A

. Night blindness
. Damaged cornea

230
Q

What is the effect of vitamin C deficiency!?

A

. Scurvy

231
Q

What is the effect of vitamin D deficiency!?

A

. Rickets, caused by weak bones

232
Q

What is the function of water as a component of a balanced diet !?

A

. it is an essential solvent (things can be dissolved in it) It is used to transport the components of blood and is crucial for temperature regulation.

Eg: sweating

233
Q

What is the function of fibre as a component of a balanced diet !?

A

. Helps the movement of food through the intestines, preventing, constipation and bowel cancer

234
Q

Sources of fibre !?

A

. Fruit and vegetables, along with grains are all good sources of fibre as they all contain cellulose.

235
Q

Put these in order:
. Egestion
. Digestion
. Absorption
. Ingestion

A

Ingestion➡️digestion➡️absorption➡️ ➡️Egestion

236
Q

What is the definition of egestion !?

A

. The expulsion of faeces through the anus. In other words, it is the removal of undigested food from the body.

237
Q

What is the definition of excretion !?

A

. The removal of waste substances produced by chemical reactions in the body for example, carbon dioxide (removed by lungs) and urea.

238
Q

What do carbohydrases act upon !?

A

. Carbohydrates

239
Q

What do proteases act upon !?

A

. Proteins

240
Q

What do Lipases act upon !?

A

. Lipids

241
Q

What is the end product, made by carbohydrases !?

A

. Smaller carbohydrate molecules, E.g. glucose

242
Q

What is the end product, made by proteases !?

A

. Amino acids

243
Q

What is the end product, made by lipases !?

A

. Glycerol +3 fatty acids

244
Q

In what part of the AC is amylase found !?

A

. Mouth
And
. Duodenum

245
Q

In what part of the AC is pepsin found !?

A

. Stomach

246
Q

In what part of the AC is lipase found !?

A

. Duodenum

247
Q

In what part of the AC is trypsin found !?

A

. Duodenum

248
Q

In what part of the AC is maltase found !?

A

. Duodenum

249
Q

In what part of the AC is peptidase found !?

A

. Duodenum

250
Q

Where is the source of the enzyme amylase!?

A

. Salivary glands
And
. Pancreas

251
Q

Where is the source of the enzyme pepsin!?

A

. Gastric glands in stomach wall

252
Q

Where is the source of the enzyme lipase!?

A

. Pancreas

253
Q

Where is the source of the enzyme trypsin!?

A

.pancreas

254
Q

Where is the source of the enzyme maltase!?

A

. Lining of duodenum

255
Q

Where is the source of the enzyme peptidase!?

A

. Lining of duodenum

256
Q

What digestive action does amylase perform !?

A

. Starch to maltose

257
Q

What digestive action does pepsin perform !?

A

. Proteins to peptides

258
Q

What digestive action does lipase perform !?

A

. Lipids to fatty acids + glycerol

259
Q

What digestive action does trypsin perform !?

A

. Proteins to peptides

260
Q

What digestive action does maltase perform !?

A

. Maltose to glucose

261
Q

What digestive action does peptidase perform !?

A

. Peptides to amino acids

262
Q

Where is the gas exchange system located !?

A

. In the thorax

263
Q

Describe the structure of the thorax, including the ribs, intercostal muscles, diaphragm, trachea, bronchi, bronchioles, alveoli, and pleural membranes

A
264
Q

Describe the trachea

A

When we breathe in air passes down the trachea, this tube is surrounded by C-shaped rings of cartilage. These keep the trachea open but make swallowing easier.

265
Q

Describe the bronchi:

A

The bronchi are two tubes that lead to the lungs. These Bronchi are also surrounded by cartilage rings.

266
Q

Describe the bronchioles

A

Bronchioles are smaller tubes which carry a deep into the thorax

267
Q

Describe the alveoli

A

At the end of each bronchiole, there are microscopic air sacs, the alveoli these are the site of gas exchange

268
Q

Describe the pleural membrane

A

The lungs are surrounded by the plural membrane. This forms a layer between the lungs in the thorax walls . They form an airtight seal and prevent the lungs from sticking to the thorax wall as they inflate and deflate.

269
Q

Describe the role of the ribs

A

The ribs help protect the organs in the thorax

270
Q

Describe the role of the intercostal muscles

A

Intercostal muscles between the ribs, help to connect the bones and are important in moving air into and out of the lungs

271
Q

Describe the role of the diaphragm

A

It’s a domed sheet of muscle and fibrous tissue. It’s also important in moving air into and out of the lungs.

272
Q

What is the definition of ventilation !?

A

Ventilation is the process of moving air into and out of the lungs

273
Q

Describe the process of inhalation

A

.The diaphragm contracts, moving down and flattening
. Intercostal muscles contract, moving rib cage up and out.
. This causes the volume of the thorax to increase and air pressure in the thorax to fall
. Air pressure is now less than atmospheric pressure, meaning moves into the lungs.

274
Q

Describe the process of exhalation

A

. Diaphragm relaxes, moving up and doming.
. Intercostal muscles relax, moving rib cage down and in
. This causes the volume of the thorax to decrease and air pressure in the thorax to rise.
. Air pressure is now more than atmospheric pressure, meaning air moves out of the lungs.

275
Q

How are the alveoli adapted for gas exchange by diffusion?

A

. There are an enormous number of alveoli in the lungs. This large surface are = more diffusion
. Each alveolus is surrounded by network of capillaries. This maintains a high concentration gradient so = more diffusion
. The walls of the alveoli are only one cell thick . There is a small diffusion distance = more diffusion

276
Q

What are the roles of the capillaries in gas exchange in the lungs 🫁 !?

A

. They constantly carry deoxygenated blood to the Alveolus and move oxygenated blood away.

277
Q

What are the biological consequences of smoking in relation to the lungs?

A

Tobacco smoke contains carbon monoxide. This irreversibly binds to haemoglobin reducing the amount of oxygen transported to the blood.
. Chemicals in tobacco, destroy cilia. At the same time mucus production will increase, in response to the smoke, The mucus cannot be moved out of the airways quickly (no cilia) so builds up causing smokers cough also increasing the risk of infection (bronchitis)
. Smoke also reaches the alveoli damaging them, decreasing the surface area for gas exchange, so less oxygen defuses into the blood (emphysema)

278
Q

What are the biological consequences of smoking in relation to the CHD?

A

. smoking increases blood pressure and increases the risk of fatty deposits forming.

279
Q

What is the danger of a build up of fatty deposits in your artery walls !?

A

. The fatty deposits narrow the lumen of the artery. This means the narrow coronary arteries have a reduced blood flow to the heart muscle cells. This means that the heart muscle cells receive less oxygen for aerobic respiration and anaerobic respiration increases. Lactic acid builds up, poisoning the heart muscle cells and causing a heart attack.

280
Q

practical : investigate the effects of exercise on breathing

A

Count the number of breaths someone takes in one minute at rest, then ask you subject to exercise e.g. jogging on the spot for five minutes count. The number of breaths they take the first minute after exercise.

. You need to carry out the experiment and lots of people
. control variables: age, gender, fitness, type of exercise and length of exercise

281
Q

practical: determine the composition of inhaled and exhaled air

A

. Using a t-tube arrangement, going from a mouthpiece into two conical flasks, bubble inhaled and exhaled air through an indicator.
. using lime water, milky white in exhaled air and remains colourless in inhaled air test tube

282
Q

What does the Phloem transport!?

A

. Phloem transports sucrose and amino acids from the leaves to the growing points or storage areas.

283
Q

What are the growing points of a plant!?

A

. The tips of the shoots and flowers

284
Q

What are the storage areas of a plant !?

A

. Roots or bulbs

285
Q

Where are sucrose and amino acids made in plants !?

A

. In the leaves

286
Q

How does the phloem transport sucrose and amino acids from the leaves !?

A

. The phloem consist of living cells
. Tubes are formed by cells that are arranged to end, but have cell walls made of Cellulose
. moving the sucrose and amino acids around the 🌱 (up and down the stem) requires energy. This is called translocation.

287
Q

What does the xylem transport!?

A

. Transports water and mineral ions from the roots to the leaves.

288
Q

How does the xylem transport water and mineral ions from the roots to the leaves !?

A

. The xylem is made up of thick walled dead cells which contain no cytoplasm. They are completely hollow and arranged End to end

. Cell walls contain lignin, which is waterproof.

. The end walls have broken down, so they form a continuous transport system through the plant.

289
Q

What is the use of the nitrate ions transported by the xylem in a plant !?

A

. Nitrate ions are needed to make amino acids and proteins

290
Q

What is the use of the magnesium ions transported by the xylem in a plant !?

A

. Magnesium ions are needed to make chlorophyll.

291
Q

How is water absorbed by the root hair cells !?

A

. RHCs are thin walled and have hair like extensions that increase the surface area of the root epidermis .The water has some solutes dissolved in it, but their concentration is much lower than the concentrations of the solute inside the root hair cells. The soil water has a higher concentration of water molecules and water will enter the cell by osmosis

292
Q

What is the function of a root hair cell !?

A

. the function of a root hair is to absorb water and mineral ions from the soil

293
Q

What is the main site of water Reabsorption for a plant !?

A

. Root hair cells (are the main site of water absorption by the root)

294
Q

What is transpiration !?

A

. Transpiration is the evaporation of water from the surface of a plant

295
Q

What four factors affect the rate of transpiration !?

A

. Temperature
. Humidity
. Windspeed
. Light intensity

296
Q

How does temperature affect the rate of transpiration !?

A

. On a hot day, water will evaporate quickly from the leaves of a plant as the water molecules have more kinetic energy
. Transpiration will increase as temperature increases.

297
Q

How does Humidity affect the rate of transpiration !?

A

. humid air contains a lot of water vapour. There is a small a concentration gradient so transpiration slows down.
. In dry air the diffusion of water vapour from a leaf to the atmosphere will be fast.
. Transpiration, therefore increases if humidity decreases

298
Q

How does wind speed affect the rate of transpiration !?

A

. In still air the area around a transpiring leaf will become saturated with water vapour, so no more can escape from the leaf, meaning transpiration is slower.
. In moving air, water vapour is blown away from the leaf as fast as it diffuses out. Speeding up transpiration.
. Transpiration increases as wind speed increases.

299
Q

How does Light intensity affect the rate of transpiration !?

A

. Light itself does not affect evaporation, but in daylight, the stomata of leaves are open to supply carbon dioxide for photosynthesis. Allowing more 💦 to diffuse out of the leaves and into the atmosphere.

300
Q

practical: investigate the role of environmental factors in determining the rate of transpiration from a leafy shoot

A
  1. The potometer must be set up underwater
  2. Cut the stem of a shoot
  3. Put the shoots them into a bong, grease the joint with plenty of petroleum jelly
  4. Put the bung into the potometer
  5. And make sure the tap is closed and it’s full of water, No bubbles. Then lift the potometer out of the water.
  6. Leave the end of the capillary tube without water until an air bubble forms, then put the end into a beaker of water
  7. You can measure the transpiration rate as distance the bubble travels in five minutes (you should take a number of readings and calculate a mean rate).
301
Q

Why does a potometer need to be set up under water!?

A

This prevents any air bubbles from entering the system and blocking the xylem

302
Q

How do you create windy conditions during a potometer experiment !?

A

. Using a hairdryer on cold

303
Q

How do you create humid conditions during a potometer experiment !?

A

. Using a clear plastic bag

304
Q

How do you vary light intensity during a potometer experiment !?

A

. Darkness

305
Q

Label:

A

A= aorta
B=pulmonary artery
C= pulmonary vein
D= left atrium
E= bicuspid valve
F= left ventricle
G= semi-lunar valve
H= semi-lunar valve
I= right ventricle
J= tricuspid valve
K= inferior vena cava
L= right atrium
M= superior vena cava

306
Q

What is the function of the right side of the heart !?

A

. The right side of the heart pumps deoxygenated blood to the lungs.

307
Q

What is the function of the left side of the heart !?

A

. The left side of the heart pumps oxygenated blood to the body.

308
Q

Why is the left ventricle wall thicker than that of the right !?

A

. The left ventricle wall is much thicker than the right ventricle, allowing it to pump blood at high-pressures so that the blood can travel around the whole body.

309
Q

How does the heart pump blood !?

A

. The two sides of the heart contract and relax at the same time, the atria contract emptying blood into the ventricles. The ventricles, then contract pushing blood into the arteries valves close to ensure blood flows in the correct direction.

310
Q

What part of the brain controls heart rate !?

A

. The medulla

311
Q

Why does heart rate increase during exercise!?

A

. If we exercise, our muscles need more glucose and oxygen for aerobic respiration, the heart rate increases so that more blood travels to the muscles.

312
Q

How does heart rate change during exercise!?

A

. When exercise starts, muscles produce more carbon dioxide in aerobic respiration.
.Sensors in the aorta detect this increase
.They send nerve impulses to the medulla
. An accelerator nerve increases heart rate
. More blood supply to the muscles to meet increased aerobic respiration

313
Q

What hormone increases heart rate when we are stressed (angry or afraid) !?

A

. Adrenaline

314
Q

What are the 5 factors that make coronary heart disease more likely !?

A

. Diet
. Smoking
. High blood pressure.
. Obesity
. Lack of exercise.

315
Q

How does poor diet make CHD more likely!?

A

. Eating lots of saturated fat increases blood cholesterol and increases the risk of fatty deposits. 

316
Q

How does smoking make CHD more likely!?

A

. Increases the blood pressure and increases the risk of fatty deposits forming

317
Q

How does high blood pressure make CHD more likely!?

A

. It damages, the artery lining and increases the risk of fatty deposits forming. High salt levels in your diet increase the risk of high blood pressure.

318
Q

How does obesity make CHD more likely!?

A

. Being obese will increase blood pressure and may be linked to poor diet.

319
Q

How does lack of exercise make CHD more likely!?

A

. Causes high blood pressure.

320
Q

What is the structure of an artery!?

A

. Thick outer wall.
. Thick layer of elastic tissue.
. Thick layer of muscular tissue.
. Small lumen

321
Q

Why is the thick outer wall of an artery beneficial to its function !?

A

. Can transport blood at high-pressure without bursting.

322
Q

Why is the thick layer of elastic tissue of an artery beneficial to its function !?

A

. Elastic tissue allows artery to stretch and recoil to keep blood flowing at high-pressure

323
Q

Why is the thick layer of muscular tissue of an artery beneficial to its function !?

A

. The thick layer of muscular tissue helps to control the flow of blood by widening and narrowing

324
Q

What is the structure of a vein!?

A

. Fairly thin outer wall
. Then layer of muscle and elastic tissue
. Semi lunar valves

325
Q

Why is the fairly thin outer wall of a vein beneficial to its function !?

A

. Blood is flowing at a lower pressure, so thick wall not needed.

326
Q

Why is the thin layer of muscle and elastic tissue of a vein beneficial to its function !?

A

. Wall can contract to keep blood flowing.

327
Q

Why is the semilunar valves of a vein beneficial to its function !?

A

. Prevents blood flowing backwards.

328
Q

What is the structure of a capillary !?

A

. Wall is one cell thick.

329
Q

Why is the one cell thick wall of a capillary beneficial to its function !?

A

. Short distance for diffusion of substances from blood into tissues.

330
Q

Label:

A
331
Q

What are the waste products of metabolism!?

A

. Carbon dioxide
. Oxygen
(form the stomata of a leaf)

332
Q

Label:

A
333
Q

What is decomposition!?

A

. Protein in dead plants and animals is broken down.
. Ammonia is released into the soil.

334
Q

What is nitrification!?

A

Ammonia is converted into nitrates and nitrites are converted into nitrates

335
Q

What is denitrification!?

A

. Nitrates are converted into nitrogen gas (denitrification reduces the amount of nitrate in the soil and therefore makes the soil less fertile)

336
Q

What is nitrogen fixation!?

A

. Nitrogen gas is converted to ammonia in bacteria which is used to make proteins, when the bacteria die the proteins decompose, releasing ammonia back into the soil.

337
Q

Which bacteria carries out the process of decomposition!?

A

. Decomposing bacteria.

338
Q

Which bacteria carries out the process of nitrification!?

A

. nitrifying bacteria.

339
Q

Which bacteria carries out the process of denitrification!?

A

. Denitrifying bacteria.

340
Q

Which bacteria carries out the process of nitrogen fixation!?

A

Nitrogen fixing bacteria, (found in soil, and in root nodules of plants)

341
Q

What is a cell !?

A

. Cells are the smallest functional unit of life and contain a number of organelles

342
Q

What is an organelle !?

A

A structure that carries out a specific process the cell needs to survive

343
Q

What is a tissue !!

A

Tissues are groups of similar cells, which work together to carry out the same function

344
Q

An example of a tissue:

A

Muscle tissue

345
Q

What is an organ!?

A

Organs are made up of several different tissues working together to carry out a more complex function.

346
Q

What are organ systems !?

A

Organ systems are made up of several different organs working together to carry out a complex function essential to life

347
Q

What are stem cells !?

A

These are not specialised to a particular job, but are able to divide many times by mitosis to make new cells

348
Q

All cells begin as…

A

. “stem cells”

349
Q

What is a specialised cell !?

A

A cell which has the structures and proteins needed to carry out a specific job in the organism

350
Q

How do stem cells become specialised cells !?

A

They differentiate (develop new features.

351
Q

What controls differentiation !?

A

differentiation is controlled by genes

352
Q

What happens to genes during differentiation !?

A

During differentiation genes are ‘switched off’ (silenced) so that they cannot be transcribed. This ensures the only proteins produced in the specialised cell are the ones needed to carry out its particular job

353
Q

How many types of stem cells are there in humans !?

A

In humans there are two types of stem cells:
- embryonic
- adult

354
Q

What is an embryonic stem cell !?

A

Embryonic stem cells are found in the early form of the embryo. They can differentiate into any type of cell

355
Q

What is an adult stem cell !?

A

. Adult stem cells are present in some tissues in organisms. There are several different types. They divide by mitosis and each type of stem cell can differentiate into a few different types of specialised cell

356
Q

An example of an adult stem cell:

A

Bone marrow stem cells

( can only form blood cells and bone cells )

357
Q

What are the uses of stem cells !?

A

. Stem cells can potentially be used to:

-treat many different diseases

  • repair damaged tissues
  • and even grow new organs for transplant
358
Q

Use of adult stem cells:

A

Currently we can transplant adult stem cells

359
Q

Example of the use of adult stem cells:

A

If someone has a damaged immune system ( perhaps due to cancer/ Leukaemia) they may receive a bone marrow transplant.

360
Q

advantage of adult stem cells:

A

. They are easy to collect for treatment

361
Q

disadvantage of adult stem cells:

A

. They can only become a limited number of cell types

362
Q

Uses of embryonic stem cells:

A

Scientists collect embryonic stem cells and culture them- grow large numbers in a lab. They are investigating how to instruct these cells to form different types of tissue for medical treatment

363
Q

Disadvantages of embryonic stem cells:

A

Many people object morally, as the cells come from extra embryos which were not used in IVF treatments

( parents choose to donate these embryos to research, however, they could potentially have developed into humans )

364
Q

What is IVF !?

A

Where eggs are fertilised in a lab, and some embryos are implanted into the uterus

365
Q

What is the function of carbohydrates in the body !?

A

. Fuel for respiration

366
Q

Label:

A

A:upper epidermis
B:xylem
C:phloem
D:stomata
E:cuticle
F:palisade (mesophyll)
G:spongy mesophyll
H:lower epidermis
I: guard cells

367
Q

How is a leaf adapted for photosynthesis !? (Surface area)

A

The leaf has a large surface area and is thin, to maximise absorption of sunlight by the photosynthetic cells.

368
Q

How is a leaf adapted for photosynthesis !? (Stomata)

A

It increases the number of stomata so that carbon dioxide can diffuse quicker (they provide a short diffusion distance for carbon dioxide)

369
Q

How is a leaf adapted for photosynthesis !? (upper epidermis)

A

The upper epidermis is transparent, allowing light to penetrate the mesophyll

370
Q

How is a leaf adapted for photosynthesis !? (palisade cells)

A

The palisade cells are long, thin and tightly packed. They contain large numbers of chloroplasts. This maximises the absorption in sunlight energy.

371
Q

Where is the plant is the main site of photosynthesis !?

A

The palisade mesophyll

372
Q

What is the role of the stomata !?

A

. Stomata allow gases to diffuse into the air spaces of the leaf

373
Q

How is a leaf adapted for photosynthesis !? (xylem)

A

The xylem transports water (absorbed in the roots) into the leaves. This then provides a short distance for water to diffuse into the photosynthesising cells

374
Q

How is a leaf adapted for photosynthesis !? (phloem)

A

The phloem vessels transport sugars made in photosynthesis to other parts of the plant

375
Q

What do plants need to grow !?

A

. Mineral ions

376
Q

What do plants need for chlorophyll !?

A

. Magnesium ions

377
Q

What do plants need for amino acids !?

A

. Nitrate ions

378
Q

Who needs more energy a pregnant woman or a teenage boy !?

A

. On average a teenage boy needs more energy than a pregnant woman ( for growth )

379
Q

What is energy measure in !? (unit)

A

. Kilojoules (kj)

380
Q

What do we use our energy for !?

A

. Around 70% of energy we use everyday is just to keep our body running ( to keep our heart beating, transport nutrients-active transport- + repair our cells)

. The remaining 30% can be used for extra work + activities eg: walking or running

381
Q

What organisms possess an alimentary canal !?

A

Humans and all mammals

382
Q

What is the purpose of the alimentary canal !?

A

Food is ingested, digested, absorbed and egested from this canal for the purpose that the food can be assimilated

383
Q

Label:

A
384
Q

What organs in the alimentary canal taken together produce the small intestine

A

. Duodenum
. + ileum

385
Q

What organs in the alimentary canal taken together produce the large intestine

A

. Colon
. + anus

386
Q

Definition of ingestion:

A

. Taking food through the mouth and swallowing

387
Q

Definition of digestion:

A

. Breaking down large insoluble molecules in food into smaller pieces (physical digestion) and smaller, soluble molecules (chemical digestion)

388
Q

Definition of absorption:

A

Movement of small soluble molecules out of the gut and into the blood by diffusion and active transport

389
Q

Definition of egestion:

A

Passing out undigested food through the anus

390
Q

Definition of assimilation:

A

. Building larger biological molecules from the small soluble molecules, in all cells

391
Q

What is the first structure in the alimentary canal !?

A

The mouth

392
Q

What takes place in the mouth !?

A

. This is where Ingestion takes place

. Digestion also begins here

393
Q

What is the definition of digestion!?

A

. Digestion, the breakdown of large insoluble molecules into small soluble molecules

394
Q

What mechanical digestion takes place in the mouth !?

A

Food here is broken up into smaller pieces in the mouth by chewing

395
Q

What is the benefit of chewing your food !?

A

It increases the surface area for enzymes and also prevents discomfort when swallowing

396
Q

What chemical digestion takes place in the mouth !?

A

Saliva is released into the mouth by the salivary glands. It makes food easier to swallow, and also contains the enzyme amylase.

397
Q

What is the role of the enzyme amylase !?

A

Amylase breaks down the starch to maltose

STARCH➡️(amylase)➡️MALTOSE

398
Q

What is the optimum pH for the enzyme amylase!?

A

Amylase works best at a neutral pH, so is denatured when it reaches the stomach and stops working

399
Q

What is a bolus !?

A

Before swallowing the food is shaped into a ball by the younger and moved towards the back of the mouth

( the ball is called a bolus)

400
Q

What is the epiglottis !?

A

There is a flap called the epiglottis which blocks the food from entering the trachea

401
Q

What is the oesophagus !?

A

The oesophagus is a long tube that connects the mouth to the stomach

402
Q

How is food moved down the oesophagus !?

A

. Food is pushed down by peristalsis.

(Food is also moved by peristalsis along the small and large intestines)

403
Q

Describe the process of peristalsis

A

Two sets of muscles push food down the oesophagus. The circular muscles contract behind the bolus, pushing it along. When the longitudinal muscles contract they make the oesophagus wider

404
Q

What glands within the stomach secret the enzyme pepsin ?!

A

The gastric glands

405
Q

What is the function of the enzyme pepsin !?

A

. It begins the process of digesting proteins into peptides (shorter chains of amino acids)

PROTEIN➡️(pepsin)➡️PEPTIDE

406
Q

How do our bodies maximise contact between enzymes and food within the stomach !?

A

. The stomach walls contract and causes mixing of the contents of the stomach

407
Q

What are pepsin’s optimum conditions !?

A

Pepsin’s optimum conditions are an acidic pH.

408
Q

Why are the conditions in the stomach acidic !?

A

Due to the release of hydrochloric acid by the gastric glands

409
Q

Does hydrochloric acid have a very low or very high pH !?

A

. HCl has a very low pH and would burn through the stomach if it was not covered by a mucus lining

410
Q

What is the role of hydrochloric acid !?

A

. To provide optimum pH for pepsin

. To kill many bacteria and fungi which may be present in the food we eat

411
Q

What takes place within the small intestine!?

A

. Both digestion and absorption happen in the small intestine

(Digestion happens in the first section, the duodenum)

412
Q

What is the role of the duodenum within the process of digestion !?

A

The duodenum is the final site of chemical digestion. The Pancreas makes several enzymes and secretes them into the duodenum

413
Q

What enzymes does the pancreas secrete !?

A

Trypsin:
PROTEIN➡️(trypsin)➡️PEPTIDE

amylase:
STARCH➡️(amylase)➡️MALTOSE

lipase:
LIPID(fat)➡️(lipase)➡️GLYCEROL+3 . fatty acids

414
Q

What enzymes do the glands within duodenum wall produce !?

A

maltase:
MALTOSE➡️(maltase)➡️GLUCOSE

peptidase:
PEPTIDE➡️(peptidase)➡️AMINO. .ACIDS

415
Q

Where is bile produced !?

A

. By the liver

416
Q

Where is bile stored!?

A

. In the hall bladder

417
Q

How does bile reach the duodenum !?

A

. Through the bile duct

418
Q

What are the two functions of bile!?

A
  1. neutralises the stomach acid.
    (enzymes in the duodenum work best at pH 7-8)
  2. emulsifies lipids, breaks down large droplets into smaller droplets
    (increasing the surface area for lipase to digest the fats)
419
Q

How is the small intestine adapted for absorption !?

A

The ileum has many folds and is covered in many finger like projections called villi

420
Q

What is the role of the villi!?

A

. They absorb small soluble molecules.
(some are absorbed by diffusion however some are also absorbed by active transport)

421
Q

What is active transport !?

A

. Absorption which moves particles against the concentration gradient using ATP

422
Q

How has the ileum adapted to increase the rate of diffusion!?

A

. Large surface area

. Short diffusion distance

. High concentration gradient

423
Q

How has the ileum increased its surface area!!

A

. Folding of ileum
. villi and microvilli (folds on the surface of cells lining the villi) all increase surface area

424
Q

How has the ileum decreases its diffusion distance !?

A

. The villi walls are one cell thick

425
Q

How has the ileum increased its concentration gradient!?

A

. The high concentration gradient is provided by the capillary network and lacteals which remove absorbed molecules

426
Q

What are the two sections of the large intestine!?

A

. Colon
And
. Rectum

427
Q

What happens at the colon !?

A

The colon is the site for all reabsorption of water

428
Q

What happens at the rectum !?

A

Faeces are stored in the rectum and then egested from the anus

429
Q

Definition of egestion:

A

. Egestion is the expulsion of faeces through the anus.
(the removal of undigested food from the body)

430
Q

Definition of excretion:

A

Excretion is the removal of waste substances produced by chemical reactions in the body

431
Q

An example of excretion:

A

. Carbon dioxide (excreted by the lungs)
. Urea (removed by the kidneys and sweat)

432
Q

Use of assimilation:

A

Assimilation takes place In all cells using the food molecules absorbed to build more complex molecules such as protein

433
Q

What do all cells need in order to be able to carry out life processes !?

A

All cells need a source of energy, this energy is provided by ATP

434
Q

What is cell respiration !?

A

Cell respiration is the process of breaking down food molecules to release ATP.
(It is a series of chemical reactions)

435
Q

What do cells use energy for !?

A

. Cell division
. Building large molecules (such as proteins)
. Contraction of muscle cells (movement)
. Transporting molecules (eg active transport)
. Maintaining body temperature

436
Q

What does aerobic respiration use oxygen for !?

A

Aerobic respiration uses oxygen to breakdown, glucose and release energy

437
Q

What is energy released as, from aerobic respiration?

A

Some energy is released as heat most is trapped in a usable form of ATP

438
Q

Word equation for aerobic respiration:

A

Glucose+ oxygen➡️carbon dioxide . +. ➕water

439
Q

Balanced chemical equation for aerobic respiration:

A
440
Q

Why does aerobic respiration release a lot of ATP !?

A

Aerobic respiration releases a lot of ATP because it completely oxidises the glucose

441
Q

What is it called when cells respire without oxygen !?

A

When cells can respire without using oxygen, this is called anaerobic respiration

442
Q

Why is less energy released during anaerobic respiration !?

A

In anaerobic respiration, glucose is not completely broken down, so less ATP and therefore less energy is released

443
Q

What other products, bar ATP, does anaerobic respiration produce !?

A

Anaerobic respiration also produces toxic waste products, which must either be excreted or broken down such as lactic acid

444
Q

What is the advantage of anaerobic respiration !?

A

The advantage of anaerobic respiration is that it allows cells to obtain a small amount of usable energy when the oxygen supply is limited

445
Q

Word equation for anaerobic respiration in fungi and plants :

A

Glucose➡️ ethanol + carbon dioxide

446
Q

Why is anaerobic respiration useful in fungi and plants !?

A

Anaerobic respiration is very useful in food production. We use yeast (a single celled fungus) in bread and alcohol production.

447
Q

How do we use anaerobic respiration to make bread and alcohol from yeast !?

A

In both processes, we supply glucose and keep the yeast in low oxygen conditions so that the cells respire anaerobically. The carbon dioxide produced forms bubbles in bread dough, causing it to rise, and the ethanol provides alcohol content in beer and wine .

448
Q

Word equation for anaerobic respiration in animals:

A

Glucose ➡️ lactic acid

449
Q

Where does anaerobic respiration take place in animals !?

A

This process occurs in muscle cells when there is a shortage of oxygen e.g. during intensive exercise

450
Q

Why does anaerobic respiration take place in animals !?

A

If muscles are worked very hard, they need large quantities of energy, more than can be provided by aerobic respiration. The glycogen stored in the muscle cells is broken down into glucose. This is respired anaerobically, providing an additional energy supply.

451
Q

What is the effect of lactic acid as a product of anaerobic respiration !?

A

Lactic acid builds up, causing cramps and diffuses from muscles into the blood

452
Q

What happens to glycogen during anaerobic respiration !?

A

The glycogen stored in the muscle cells is broken down into glucose. This is respired anaerobically, providing an additional energy supply.

453
Q

When does lactic acid become toxic !?

A

In high concentrations, lactic acid is toxic

454
Q

What happens to the lactic acid produced by anaerobic respiration !?

A

It is transported to the liver where it is oxidised

455
Q

Why do we keep breathing heavily after exercise !?

A

(Oxidation of lactic acid in the liver uses oxygen), we keep breathing heavily after exercise to supply the extra oxygen needed to dispose of the lactic acid in our bodies

456
Q

What is oxygen debt !?

A

Oxygen debt is the volume of oxygen needed to oxidise the lactic acid, in the liver

457
Q

Label :

A
458
Q

How is the central nervous system linked to sense organs !?

A

The central nervous system is linked to sense organs by nerves

459
Q

Label:

A
460
Q

What is blood !?

A

. Blood is a complex tissue

461
Q

What does blood consist of !?

A

Blood is a complex tissue, consisting of
.a liquid component (plasma)

.cell fragments, platelets

.and two types of cells, red and white blood cells

462
Q

What does plasma look like !?

A

Straw colored liquid

463
Q

What do red blood cells look like !?

A

Small red cells

464
Q

What do platelets look like !?

A

Cell fragments

465
Q

What do phagocytes (white blood cells) look like !?

A

Larger cells with a multi-lobed nucleus

466
Q

What do lymphocytes (white blood cells) look like !?

A

Cells with a very large nucleus

467
Q

What is the role of plasma in the blood !?

A

Plasma transports blood cells and many other substances, including dissolved nutrients

468
Q

What does plasma transport around the body !?

A

dissolved nutrients,

.such as glucose and amino acids

.dissolved waste products, including urea and carbon dioxide, hormones, proteins, and heat energy

469
Q

What is the role of red blood cells in the blood!?

A

To transport oxygen bound to haemoglobin

470
Q

What is the role of platelets in the blood!?

A

Platelets release chemicals when the blood is exposed to air

471
Q

What do the chemicals released by platelets when it is exposed to air do to the blood !?

A

The chemicals cause soluble fibrinogen to be converted into insoluble fibrin

472
Q

How is a clot/ scab formed !?

A

(Chemicals produced by platelets convert soluble fibrinogen into insoluble fibrin)

Fibrin forms a mesh which traps platelets in red blood cells. This is a clot.

473
Q

What is the role of phagocytes (white blood cells) in the blood !?

A

Phagocytes engulf and digest pathogens

474
Q

What is a pathogen !?

A

A pathogen is a microorganism, which causes disease

475
Q

What is the role of lymphocytes (white blood cells) in the blood !?

A

Lymphocytes *^make and release antibodies**, which bind to and destroy pathogens

476
Q

How are red blood cells specialised for their job !?

A

.Red blood cells contain haemoglobin
. They have no nucleus
. They are biconcave

477
Q

What is the advantage of red blood cells containing haemoglobin !?

A

Haemoglobin is a protein which combines with oxygen to form Oxyhemoglobin this transports oxygen to respiring cells

478
Q

What is the advantage of red blood cells havingno nucleus !?

A

Red blood cells have no nucleus, meaning that more haemoglobin can be packed into each cell and so more oxygen to be transported

479
Q

What is the advantage of red blood cells being a biconcave shape !?

A

Red blood cells are biconcave (discs with a dip in the middle. This increases the surface area: volume ratio and decreases the distance to the centre of the cell. This increases the rate of diffusion

480
Q

What is a disease !?

A

A disease is a condition that prevents the body or part of it working properly

481
Q

What are most diseases caused by !?

A

Most diseases are caused by microorganisms, pathogens

( e.g viruses and bacteria )

482
Q

How do pathogens cause a disease !?

A

By entering the body and feeding and reproducing in it, they damage the body or poison it by excreting toxic waste substances called toxins

483
Q

What are the physical barriers that attempt to stop pathogens from entering !?

A

The skin and membranes of the body

484
Q

What takes over the defense of the body if the physical barriers become damaged !?

A

If the barriers become damaged, then white blood cells take over the defence of the body

485
Q

What are the two main types of white blood cell !?

A

Phagocytes and lymphocytes

486
Q

How does a phagocyte work !?

(step by step)

A
  1. Phagocyte recognises pathogen.
  2. phagocyte engulfs, a pathogen in a process known as phagocytosis
  3. The lysozymes containing the enzymes move towards the pathogen.
  4. enzymes break down the pathogen.
  5. useful materials are absorbed
  6. waste products are removed from the phagocyte
487
Q

What is the process of phagocytosis ?

A

Phagocytes s are a type of white blood cell engulfs and digest pathogens that they encounter. This is called phagocytosis.

488
Q

What are antibodies !?

A

a special Y-shaped protein

489
Q

What produces antibodies !?

A

Antibodies are what lymphocytes produce

490
Q

What is the role of an antibody !?

A

Antibodies attach to proteins on the surface of pathogen is called antigens

491
Q

Why do lymphocytes need to make specific complementary antibodies !?

A

Each pathogen has a different shaped antigen, so the lymphocytes need to make a specific complementary antibody

492
Q

How do lymphocytes benefit organisms !?

A

Lymphocyte allow organisms to build up an immunity toward certain diseases

493
Q

How does a lymphocyte work !?
(step by step)

A
  1. lymphocytes detect pathogen’s antigens
  2. Lymphocyte identifies the correct type of antibody to make which is complimentary to the pathogen is antigen.
  3. Lymphocyte releases large numbers of correct Antibody
  4. Pathogens either clump together, resulting in death or the antibodies trigger phagocytes (some pathogens even burst)
  5. Lymphocytes produce cells that produce lots of the antibody very quickly if they detect the same pathogen again. these are called memory cells
494
Q

What are anti-toxins !?

A

. Some antibodies are specialised to combat toxins, chemicals released by pathogen, which cause cell damage these are called anti-toxins

495
Q

What are toxins !?

A

chemicals released by pathogen, which cause cell damage.

496
Q

How do most plants respond to changes in their environment !?

A

Most plants do not respond quickly they respond slowly by changing their rate of growth

(Some plants like the -Venus fly- trap can respond quickly)

497
Q

What is an example of a stimuli a plant would respond to !?

A

Plants can respond to a stimulus such as light

(plants, place near a window will grow towards the light)

498
Q

What is a tropism !?

A

The growth of a plant towards a directional stimulus is called a tropism

499
Q

What are phototropisms !?

A

Phototropisms are growth responses to light from one direction

500
Q

What is positive phototropism !?

A

Growth towards the light from a single direction is called positive phototropism

501
Q

What is the name of the hormone that controls the phototrophic growth of plants !?

A

Auxin

502
Q

Where is auxin found !?

A

Auxin, the hormone that controls controls phototropic growth is found in the top of the stem

503
Q

How does auxin cause phototrophic growth !?

A

The tip of the shoot produces the Auxin, which diffusers down the shoot to cause elongation (lengthening) of cells

504
Q

Where does auxin build up if light intensity is higher on one side of the stem !?

A

When light intensity is higher on one side of the stem, auxins buildup on the shaded side. This causes the cells on the shaded side to elongate more as a result the shoot bends towards the light

505
Q
A

A- tips are cut off, therefore no growth

B- tips covered. Therefore the stem grows directly upwards (no light reached the tip)

C- stem grows towards the light, this is called positive phototropism

506
Q

What is geotropism !?

A

Geotropism is the growth towards or away from gravity

507
Q

Are roots positively or negatively geotropic !?

A

Roots are positively geotropic

Biology, 5th Form (5 decks)

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