Paper 2 Collection Flashcards

Question 1

Q

SB6a - What is the equation for photosynthesis?

Answer

A

Carbon dioxide + Water → Glucose + Oxygen

Question 2

Q

SB6a - What is the equation for respiration?

Answer

A

Glucose + Oxygen → Carbon dioxide + Water

Question 3

Q

SB6a - What does photosynthesis do?

Answer

A

It traps energy from the sunlight and converts it to glucose

Question 4

Q

SB6a - Where does photosynthesis occur?

Answer

A

In the chloroplasts of the plant cell

Question 5

Q

SB6a - What type of reaction is photosynthesis?

Answer

A

Endothermic.
The products have more energy than the reactants.
This means they have taken in energy from the surroundings during the reactions

Question 6

Q

SB6a - Why is glucose necessary?

Answer

A

Glucose molecules are joined together to form a polymer of starch.
After photosynthesis stops, this is broken down to simple molecules which are used to form sucrose.
Sucrose is used to make:
- Starch (In a storage organ such as a potato)
- other molecules for the plant (cellulose, lipids etc.)
- Glucose for respiration (to release energy)

Question 7

Q

SB6a - How are leaves adapted for their purpose?

Answer

A

They have a broad flat shape giving them a large surface area for photosynthesis
There are lots of palisade cells near the top which are packed with chloroplasts to absorb light
Stomata allow carbon dioxide to diffuse in for photosynthesis
When there is light (during day) water flows into guard cells making them rigid and when there is less light (nighttime) The water flows out making it loose its rigidity
When it is rigid, it is open so it is only open when there is light
This means it will only allow carbon dioxide to diffuse when there is also light to conduct photosynthesis
Leaves are thin meaning carbon dioxide doesn’t have far to diffuse

Question 8

Q

SB6a - Tomayto, tomahto?

Answer

A

Stomayto, stomatoh

Question 9

Q

SB6a - Why are the stomata an example of a gas exchange system?

Answer

A

They let carbon dioxide diffuse in and let oxygen diffuse out

Question 10

Q

SB6b - What are the three main limiting factors that affect photosynthesis?

Answer

A

Carbon dioxide concentration
Light Intensity
Temperature temperature

Question 11

Q

SB6b - Why are plants less likely to grow higher up on a mountain?

Answer

A

Higher up, the air pressure is lower meaning the carbon dioxide concentration is lower

Question 12

Q

SB6b - A graph showing how increasing rate of light intensity affects rate of photosynthesis eventually levels out. Why can’t it get any higher despite light intensity increasing?

Answer

A

As the graph curves, light intensity is the limiting factor.
Once it levels out, something else is the limiting factor.

Question 13

Q

SB6b - Once the rate of photosynthesis can’t increase anymore (due to light intensity in this case) how would you increase the rate of photosynthesis?

Answer

A

Something else is the limiting factor.
Increasing the CO₂ concentration or increasing the temperature will allow the rate of photosynthesis to continue to increase.
Eventually it will level out again as something else has become the limiting factor.

Question 14

Q

SB6b - Why is it that even if temperature is the limiting factor, you’ll get to a point where increasing it won’t increase the rate of photosynthesis?

Answer

A

At a temperature that is too high, the enzymes in the plant become denatured.
They can no longer bind to their substrate and therefore processes can’t occur anymore

Question 15

Q

SB6b - What is the inverse square law, and where does it apply to?

Answer

A

The inverse square law is used to find out how light intensity chages ith distance from the source.
I: light intensity
d: distance

I(original) x d(original)² = I(new) x d(new)²

light intensity is inversely proportionate to the square of the distance

Question 16

Q

SB6b CP - Describe a method, using algae balls and hydrogen carbonate indicator, to investigate rates of photosynthesis at differing light intensities.

Answer

A

Add 20 algae balls and the same amount of indicator to as many glass bottles as you need
Compare the colour of the bottle at the start to a key to work out its starting pH (they should all be the same)
Place a tank of water between the light and the first glass to absorb the heat given off by the light
Cover one with foil so it is in the dark and place it next to the one closest to the lamp
Measure out the distances you place all of the bottles
Turn on the light and wait till you see noticable changes in the pH
Once you’ve decided to stop, work out the pH again by comparing to a key
Work out the change in pH/hour to be your rate of reaction
Plot a graph of rate of reaction vs distance from light

Question 17

Q

SB6c - Why do plants need to take in water?

Answer

A

To be used in/to:

Carrying dissolved mineral ions
Keeping cells rigid so plants don’t wilt (droop)
Cooling leaves (when it evapourates)
Photosynthesis

Question 18

Q

SB6c - How are roots adapted to absorb water?

Answer

A

Roots have root hair cells
The hairs make the surface area larger meaning there is more area for mineral ions to be quickly absorbed through water

Question 19

Q

SB6c - What is a concentration gradient and what can it cause to occur?

Answer

A

When two areas are connected in some way and having differing levels of concentration of a substance, they have a concentration gradient If this is in a fluid, diffusion can occur, where the substance moves from the area of higher to lower concentration

Question 20

Q

SB6c - What do root hair cells and root cells have between them and why?

Answer

A

They have a little tube allowing diffusion of fluids between cells

Question 21

Q

SB6c - How can some water enter the root hair cells if not through openings?

Answer

A

The root hair cells have a semi-permeable membrane meaning that osmosis can take place with the water moving down the concentration gradient into the cytoplasm of the cell

Question 22

Q

SB6c - How do plants take in mineral ions?

Answer

A

Through the water they absorb.
However as there is a higher concentration of these in the plant than in the soil, they can’t absorb it through diffusion but rather through active transport which takes up energy

Question 23

Q

SB6d - Describe the process of transpiration

Answer

A

The flow of water into a root, up the stem and out the leaves
As water on the leaves’ surface evapourates, a concentration gradient is created
This prompts water to be drawn out from the inside of the leaves through the stomata through diffusion and osmosis
They travel through the xylem down the concentration gradient
This is aided by the cohesion between the H2O molecules due to hydrogen bonds and adhesion to the walls of the xylem cell
At the root hair cells, as water moves up the xylem, water is also taken in due to the concentration gradient

Question 24

Q

SB6d - Describe the process of translocation

Answer

A

The transport of sucrose around a plant
The source is the leaf where glucose is created by photosynthesis
Glucose monomers join together to from a sucrose polymer (as only polymers can be transported this way)
The sucrose is actively transported into the phloem through a companion cell
At the top of the phloem there is a low concentration of water. So water from the xylem diffuses through pores in the cells
This water then has a high pressure so moves down the phloem taking the sucrose with it
It will then be actively transported through a companion cell to whatever cell it is needed in

Question 25

Q

SB6d - Describe the adaptations of the xylem

Answer

A

Multiple pores to allow water and mineral ions to enter and leave
dead cells, no cytoplasm and no cell walls to allow flow of water through it
rings made of lignin and thick side walls to keep the water inside

Question 26

Q

SB6d - Describe the adaptations of the phloem

Answer

A

Holes in cell walls to allow liquids to flow
No nucleus or cytoplasm as they aren’t needed and would be a waste of energy
Companion cells to pump have many mitochondria so they have energy to actively transport sucrose

Question 27

Q

SB6d - Describe how you can investigate rates of transpiration

Answer

A

A potometer is used for this. It involves using a plant attached to a rubber stopper connected to a reservoir of water and a capillary tube.
The capillary tube should have at least one bubble in it and should have a scale .
As the plant uses up water it will draw water from the tube moving the air bubble.
The speed of the bubble will allow you to calculate the rate of transpiration

Question 28

Q

SB6e - How is the structure of a leaf adapted for photosynthesis and gas exchange?

Answer

A

Leaves are broad and flat which gives them a large surface area.
Palisade cells near the top of the leaf are packed with chloroplasts to allow large amounts of light absorption.
Spongy cells create air spaces so gasses can diffuse in and out.

Question 29

Q

SB6e - Why do some plant have needle shaped leaves?

Answer

A

Small leaves result in a reduced surface area so transpiration happens more slowly.
A thick cuticle protects them from infection.
The smaller leaves helps them to withstand strong winds and a lack of water

Question 30

Q

SB6e - How do plants reduce water loss?

Answer

A

Having stomata located inside small pits
By losing leaves in winter
By closing stomata at night
Having thinner leaves

Question 31

Q

SB6f - What are the names of three main plant hormones?

Answer

A

Auxins: promote growth
Gibberellins: cause germination
Ethene: cause fruit ripening

Question 32

Q

SB6f - What are positive and negative phototropism and gravitropism?

Answer

A

Positive = towards
Negative = away
Phototropism = a response to light
Gravitropism = a response to gravity

Question 33

Q

SB6f - How does phototropism occur?

Answer

A

Auxins a produced in the tip of the shoot
As the shoot is exposed to light, auxins move to the shaded side of the root (the side away from the sun)
Here they cause the cells to elongate causing the shoot to point towards the sun

Question 34

Q

SB6g - How are auxins used by plant growers?

Answer

A

Selective weedkillers contain artificial auxins to kill plants with broad leaves.
Auxins are also used in rooting powders which cause plant cuttings to grow roots rather quickly

Question 35

Q

SB6g - What are the uses of gibberellins?

Answer

A

Produce seedless fruits
Promote flowering
Increase fruit size
Germinate seeds

Question 36

Q

SB6g - How do farmers ripen fruits once they have been removed from a tree?

Answer

A

Use ethene gas

Question 37

Q

SB6d - Describe the factors that affect transpiration.

Answer

A

Light intensity: stomata opens wider allowing water in quicker
Temperature: More evapouration means a greater concentration gradient on the leaf surface
Wind speed: Less water on leaf surface steepens the concentration gradient
Fall in humidity: As the air becomes less saturated, water vapour evapourates more easily steepening the concentration gradient

Question 38

Q

SB6f - How does gravitropism occur?

Answer

A

Auxins in the root are pulled down by gravity.
They inhibit cell elongation here causing the root to grow downwards (positive gravitropism)
Auxins in the shoot are also pulled down by gravity but here they cause cell elongation making the shoot grow upwards (negative gravitropism)

Question 39

Q

SB6f - Describe Darwin’s experiments with auxin and what can be concluded from the results.

Answer

A

Three intact shoots exposed to light. One covered with a black cap, one with a transparent cap and one normal
The one with the black cap didn’t bend towards the light while the other two did
This shows that auxins are dependent on light to work
One where the tip was removed didn’t bend towards the light.
This showed that auxins are produced in the tip of the shoot
A tip was also placed on a permeable and and impermeable base (removed from the plant)
The one on the permeable base (agar block) bent towards the light but the other didn’t
This shows that auxins need to travel further down in the plant to work

Question 40

Q

SB7a - What are hormones?

Answer

A

Hormones are chemical messengers (carried in the blood stream).
They are used in the hormonal response system which is typically slow-acting and long-lasting compared to the nervous system

Question 41

Q

SB7a - Where are hormones released? (Give examples)

Answer

A

Endocrine glands e.g:

Pituitary gland
Thyroid gland
Adrenals
Ovaries
Testes
Pancreas

Question 42

Q

SB7a - Where do hormones go to? (Give examples)

Answer

A

Target organs e.g:

Digestive system
Kidneys
Liver
Endocrine glands for other hormones (e.g growth hormone)

Question 43

Q

SB7b - What is your metabolic rate?

Answer

A

The rate at which energy stored as food is transferred by all of the reactions that take place in your body

Question 44

Q

SB7b - How do you measure resting metabolic rate?

Answer

A

At a warm room
Body at rest
Long after the person has had a meal

Question 45

Q

SB7b - What is a negative feedback system?

Answer

A

A response to an increase in one condition by causing actions that will decrease it, or vice versa (e.g response to body being too hot is to sweat to cool it down)

Question 46

Q

SB7b - Define homeostasis

Answer

A

Maintaining constant conditions in the body, typically through negative feedback

Question 47

Q

SB7b - What is thyroxine?

Answer

A

Thyroxine is a hormone that is released by the thyroid gland.
It’s target organs are many different types of cells of which it will increase the rate at which protein and carbohydrates are broken down.
This affects your metabolic rate

Question 48

Q

SB7b - How is thyroxine used as part of a negative feedback system?

Answer

A

If the concentration of thyroxine in the blood is low, the hypothalamus may release TRH
This will cause the pituitary gland to release TSH
This stimulates the thyroid gland to release thyroxine, increasing the concentration of thyroxine

Question 49

Q

SB7b - How does your body’s fight or flight system work?

Answer

A

Adrenaline is released from adrenal glands and is always in the bloodstream at a low level
A fight or flight situation will cause increased impulses from neurons which will trigger the release of large amounts of adrenaline into your blood
Adrenaline has many target organs:
- Causes the breakdown of glycogen to glucose in the liver so that there is more for cellular respiration (more energy)
- Heart contracts more rapidly and strongly increasing the heart rate and blood pressure. This moves glucose around the body quicker
- Diameter of blood vessels leading to muscles or target organs are widened to allow more blood through while the rest are narrowed to allow more to be sent to the widened vessels

Question 50

Q

SB7g - What is thermoregulation?

Answer

A

The negative feedback system that ensures our body stays at around 37°C

Question 51

Q

SB7g - What is fever/hypothermia and why is it bad?

Answer

A

Fever is when your body is above 38°C
Hypothermia is when your body is below 36°C
These are bad because the enzymes that enact most of the processes in our body that keep us alive have an optimum temperature of 37°C
So straying too far from it will stop these processes from occurring (properly) as enzymes can become denatured/ineffective

Question 52

Q

SB7g - How does the brain detect the temperature of the body?

Answer

A

In the dermis of the skin, there are temperature receptors
These feed information to the receptors in the hypothalamus in the brain

Question 53

Q

SB7g - When the body is too cold, what will happen?

Answer

A

Shivering: Muscles rapidly contract and expand. Some of the energy released form cell respiration warms you up
Vasoconstriction: Nerve signals from the hypothalamus tell the blood vessels near the surface of the skin (in the dermis) will narrow. This reduces thermal energy lost to surroundings as blood flows past
Erector muscles contract: Erector muscles in the dermis of the skin contract causing hair to stand upright. While it may not work for humans, on other mammals it traps air next t the skin for insulation

Question 54

Q

SB7g - When the body is too warm, what will happen?

Answer

A

Sweating: Your body secretes a thin layer of sweat on the epidermis of your skin. When this evaporates, it transfers energy from the body to the surroundings
Vasodilation: Nerve signals from the hypothalamus tell the blood vessels in the dermis widen. As more blood flows near the surface of the skin, more energy is transferred to the surroundings
Erector muscles relax: Hair lies flat meaning no air can be trapped and reducing the insulation (again it doesn’t make a difference for humans)

Question 55

Q

SB7h - What is osmoregulation?

Answer

A

The negative feedback system involving the balance of water and minerals in the body.
The wrong balance will result in cells taking in the wrong amounts through osmosis and being damaged

Question 56

Q

SB7h - Describe how the urinary system works

Answer

A

The urinary system removes excess amounts of substances from the blood inc. water mineral salts and urea
Renal arteries carry blood from the body to the kidney.
Once it is ‘cleaned’ renal veins carry the blood to the rest of the body
The kidneys remove excess substances from the blood to form urine
Ureters carry urine to the bladder where it is stored
Once the muscle keeping the bladder closed is released, the urine passes through the urethra to outside the body

Question 57

Q

SB7h - What is kidney failure and why is it dangerous?

Answer

A

Kidney failure is when both of the kidneys stop working properly
This means that there will be high concentration of waste products in their blood which will need to be removed by dialysis

Question 58

Q

SB7h - What is urea?

Answer

A

Urea is produced from the breakdown of excess amino acids in the liver. This is passed into the blood

Question 59

Q

SB7e - Describe the travel of glucose through the bloodstream of a non-diabetic person?

Answer

A

Glucose is released from the small intestine after digestion. As it flows into the bloodstream, the concentration rises
The pancreas detects the high levels of blood glucose and releases insulin. Now the concentration of insulin also rises
The insulin causes the liver, muscle and other cells to take up the glucose and store it as glycogen. Thus the glucose and insulin concentration reduces
Once the glucose concentration is too low, the pancreas releases glucagon.
This causes all the cell that contain glycogen to convert this back into glucose which is released into the blood
This is a negative feedback system

Question 60

Q

SB7e - What is type 1 diabetes and how can it be dealt with?

Answer

A

Pancreatic cells don’t produce insulin as they have been destroyed by the body’s immune system
This means they cannot control blood glucose levels naturally
A type 1 diabetic would have to inject insulin into the fat layer below the skin to reduce blood glucose levels
(Typically non-genetic)

Question 61

Q

SB7f - What is type 2 diabetes?

Answer

A

Insulin releasing cells don’t produce enough insulin or target organs don’t respond to insulin
Can be genetic or due to lifestyle

Question 62

Q

SB7f - Why can being physically active help with type 2 diabetes?

Answer

A

Physical activity increases cellular respiration that takes place in your body
This takes up glucose form your blood reducing the need for insulin
this lowers your blood glucose level

Question 63

Q

`SB7f - What is the relationship between T2 diabetes and average body mass?

Answer

A

The higher your body mass, the higher the risk of T2 diabetes.
These factors are correlated

Question 64

Q

SB7f - How do you calculate BMI?

Answer

A

BMI = mass (kg) ÷ height (m²)

Answer 65

A

waist measurement ÷ hip measurement

Answer 66

A

While both have a correlation with risk of T2 diabetes, BMI doesn’t account for muscle mass.

Answer 67

A

The cycle of changes that take place in a women’s reproductive system for about 28 days
Starts with puberty (around 12) and ends with menopause (around 50)
Prepares the body for the fertilisation of an egg and pregnancy

Answer 68

A

Days 1-5ish: Menstruation is when the lining of the uterus breaks down and is lost with an unfertilised egg
Days 10-12ish: The uterus lining starts to thicken again
Days 13-15: The new egg is released from the ovary
Days 16-28: Uterus lining continues to thicken
Day 23ish: The egg cell travels along the oviduct to the uterus

Answer 69

A

(Follicle stimulating hormone) is involved in the maturing and growth of the egg follicle
It is released from the pituitary gland and is inhibited by higher level of progesterone (which is released after the follicle becomes a corpus luteum)
Highest levels around day 4 and 12

Answer 70

A

(Luteinising hormone) is involved in causing the egg to be release
It is released from the pituitary gland and is inhibited by higher levels of progesterone but stimulated by higher levels of oestrogen
Highest levels around day 13 (with oestrogen)

Answer 71

A

Oestrogen: Causes the uterus lining to thicken and stimulates releases of LH
- Highest around day 13
Progesterone: Inhibits release of LH and FSH
Both reduce in concentration after the menstruation but stay constant if the egg is fertilised

Answer 72

A

Release progesterone and oestrogen-like hormones to ‘trick’ the body into thinking the egg is fertilised (due to no drop in concentration after day 28) and stops ovulation
Thickens the mucus at the cervix making it harder for sperm to pass through

Answer 73

A

The prevention of fertilisation. e.g:

Condom
Diaphragm or cap
Hormonal pills / implants

Answer 74

A

Using ART (Assisted reproductive technology) (Inc. IVF)

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Answer 75

A

Used on women who rarely or never release an egg, this uses a drug that increases levels of FSH and LH, this prepares the body for the egg by thickening the lining and stimulates the release of an egg

Answer 76

A

In vitro fertilisation is when the egg is fertilised in a lab and the embryo is re-inserted into the women’s uterus:

Egg follicle maturation is stimulated by hormones
Eggs are released by many follicles and they are taken from the ovary
Sperm cells are taken from the man
The egg cells and sperm cells are allowed to combine in a petri dish for fertilisation
One or two healthy embryos are re-inserted into the uterus

Answer 77

A

Blood containing waste is taken form the vein and passed through a dialysis machine
Dialysis machine contains fluid which has the same glucose concentration as blood plasma
There is a semi-permeable membrane which allows the waste and excess substances to leave the blood through osmosis (due to conc. gradient)
The same level of glucose on either side of the membrane means there won’t be a net loss/gain
The ‘cleaned’ blood is sent back to the person’s veins

Answer 78

A

Another person’s kidney is used to replace a faulty one. However:

This takes a lot of surgery and may not be suitable for weaker patients
Like all cells, the have antigens on them and the recipient’s immune system may attack it. This is called rejection
Even with a successful organ donation, the patient needs to be on lifelong medication to weaken their immune system making them more susceptible to other infections

Answer 79

A

Anti diuretic hormone is used to control the water concentration of urine as it leaves the kidney
When the pituitary gland detects a low water concentration in the blood it releases ADH
ADH makes the collecting duct’s walls more permeable allowing more osmosis of water out through it and making the urine more concentrated with urea
A lack of ADH means the collecting duct’s walls are less permeable. Less water leaves through osmosis and so the urine is more dilute

Answer 80

A

Nephrons are tiny microscopic tubes in the kidney where urine is made

Answer 81

A

Protein pumps containing mitochondria providing energy for active transport
large surface area of contact between nephron and capillaries (convoluted tubes) and…
micorvilli on the first convoluted tube. These increase surface area:volume ratio increasing rate of osmosis

Answer 82

A

Blood flows through a network of capillaries (glomerulus) in the bowman’s capsule
Here, the smaller molecules (water urea glucose) move into the nephron while larger particles (protein blood cells) stay
This is filtration

Answer 83

A

Selective re-absorption
At the first convoluted tube, glucose and some mineral ions are reabsorbed
However, if a person is diabetic, not all the glucose will be reabsorbed leaving some in the urine

Answer 84

A

Selective re-absorption
Here, water is selectively reabsorbed depending on how much is needed in the bloodstream
Some mineral ions are also reabsorbed

Answer 85

A

Selective re-absorption
Some water is reabsorbed depending on how much is needed (ADH dependent)
The collecting duct takes the filtered fluids along from the filtered fluids from the second convoluted tube to the ureter
Here it is urine and contains excess water, urea and other substances

Answer 86

A

Using active transport to transfer substances back from the nephron into the bloodstream

Answer 87

A

Your metabolism

Answer 88

A

They must be excreted so that they don’t cause any problems

Answer 89

A

Urea
Carbon dioxide

Answer 90

A

Glucose
Amino Acids
Oxygen

Answer 91

A

Diffusion

Answer 92

A

Thin: So particles don’t have to diffuse far
Large surface area: More room to allow particles to diffuse through

Answer 93

A

Oxygen and glucose diffuses out and carbon dioxide diffuses in at a certain point
The blood then continues to flow
This means that concentration gradient at the diffusion point is maintained
This allows diffusion to continue happening

Answer 94

A

Transport systems are needed to take substances towards the centre of the body as diffusion from the outside to the centre of the body would take too long

Answer 95

A

The heart
Veins
Arteries
A network of fine capillaries

Answer 96

A

Surface area ÷ Volume

Answer 97

A

A higher surface area means more area through which particles can diffuse, but a larger volume takes longer to be filled up

Answer 98

A

As cells get bigger, their SA:V ratio gets smaller.
This means it will take longer and longer for substances to enter the cell

Answer 99

A

The lungs have millions of aveoli which increase the surface area while maintaining the volume.
This increases the SA:V ratio increasing rate of gas exchange

Answer 100

A

One cell thick wall allowing for easy diffusion
Large SA:V ratio due to its shape

Answer 101

A

Concentration (g/dm³)

=

mass of solute (g) / volume of solution (dm³)

Answer 102

A

The steeper the concentration gradient (Greater the difference in concentration) the higher the rate of diffusion due to a larger net movement of particles in the same time

Answer 103

A

They have a linear directly proportional relationship

rate of diffusion ∝ concentration difference

Answer 104

A

A higher surface area means that particles have more area to pass through.
This means that more particles can move through a membrane at one time.
This increases the overall rate of diffusion but doesn’t change the speed at which particles move

Answer 105

A

rate of diffusion ∝ surface area

Answer 106

A

A thicker membrane means that particles have a longer distance to travel.
This means that the rate of diffusion will be slower

Answer 107

A

rate of diffusion ∝^-1 thickness of membrane

or

rate of diffusion ∝ 1 ÷ thickness of membrane

Answer 108

A

Fick’s law shows the relationship between the three factors that affect rate of diffusion.

Answer 109

A

Heart: Pumps blood around the body
Arteries: Take blood away from the heart
Capillaries: Fine networks taking blood to and through tissue
Veins: Takes blood back to the heart

Answer 110

A

Narrow lumen (tube)
Thick elastic and muscle fibres
This helps it withstand high pressures
Recoil due to elasticity helps the blood continue to be pumped

Answer 111

A

Capillaries have very narrow lumen (tubes) as they are carrying very little blood
They have walls only 1 cell thick to allow for faster diffusion

Answer 112

A

Valves to ensure blood flows in one direction
Thin walls as pressure is low
Wide lumen (tube) to reduce pressure

Answer 113

A

Arteries have blood flowing at a high pressure and this ensures blood flows in the right direction
This is helped by the elasticity
Veins have blood flowing at a low pressure and so blood isn’t forced to travel in the right direction
Valves ensure blood flows in the correct direction

Answer 114

A

Valves are like one way doors
Skeletal muscles help blood move along the veins
When blood is flowing in the correct direction, valves are open
When muscles are relaxed, blood can easily flow in the wrong direction
The moment any blood starts to flow in the wrong direction, the valves close, stopping blood from flowing this way

Answer 115

A

Erythrocytes

Answer 116

A

Erythrocytes (RBC)
White blood cells
Platelets
Plasma

Answer 117

A

Packed with haemoglobin which oxygen binds to allowing it to be transported
Biconcave shape to increase surface area for effective diffusion
No nucleus to make more space for haemoglobin and oxygen
Will turn a brighter shade of red when more oxygen is bound

Answer 118

A

Phagocytes: Surround and consume foreign cells
Lymphocytes: Release antibodies to attack foreign cells

Answer 119

A

Water
Carbon dioxide
Glucose
Urea
Other dissolved minerals

Answer 120

A

Platelets are tiny fragments of cells that produce substances to allow the blood to clot when injured

Answer 121

A

When blood stops flowing through the heart properly, it can damage the heart muscles.
This can cause a heart attack, also known as cardiac arrest.
If the heart stops working completely, an electric shock (i.e. a defibrillator) can get it to work again

Answer 122

A

You don’t need to know everythign on this diagram ,and a couple of stuff (e.g. the septum) is missing. But you need to have a general idea of what it looks like

Answer 123

A

Firstly, blood from the upper body enters the heart through the superior vena cava; while blood from the lower body enters through the inferior vena cava
This travels into the right atrium and through the ventricle
The blood leaves through the pulmonary artery into the lungs where it becomes oxygenated
It then re-enters the heart through the pulmonary veins
Here it travels through the valves and left ventricle before leaving through the aorta

Answer 124

A

You are looking at the diagram as if you are looking at a person (left on right and v/v)

Answer 125

A

It has to pump blood to all around the body rather than just to the lungs and so requires more strength

Answer 126

A

The volume of blood pushed into the aorta per beat

Answer 127

A

Cardiac output (litres/min)

=

Stroke volume (litres/beat) x heart rate (beats/min)

Answer 128

A

Moving
Keeping warm
Production and breaking down substances

Answer 129

A

A series of reactions that uses glucose to provide energy for the body.
It is exothermic

Answer 130

A

In the mitochondria

Answer 131

A

Breathing in adds oxygen into the blood flow
As the blood passes the small intestine, it absorbs glucose from digested food
When the blood reaches a cell, the cell takes in the glucose and oxygen in exchange for carbon dioxide and water
The blood takes this carbon dioxide back to the lungs where it is breathed out

Answer 132

A

Glucose + Oxygen → Carbon dixoide + Water (+ energy)

Answer 133

A

It releases energy to its surroundings and the products have less energy than the reactants

Answer 134

A

Faster breathing allows more oxygen to be breathed in and diffused into the blood
This provides more oxygen for cells to respire more effectively
It also gets rid of more carbon dioxide

Answer 135

A

Glucose → Lactic acid (+energy)

Answer 136

A

Anaerobic respiration occurs in a deficit of oxygen
During strenuous exercise, your cells may need more oxygen than can be provided leading to anaerobic respiration occuring

Answer 137

A

It produces less energy than aerobic respiration
Lactic acid building up in muscles can cause cramps and damage
Muscles can tire quickly

Answer 138

A

Anaerobic respiration can provide short sharp bursts of energy without needing a sudden increase in oxygen supply

Answer 139

A

Extra oxygen is needed to replace what has been lost
Extra oxygen is required to provide energy to get rid of lactic acid

Answer 140

A

Set up the test tube with a bung attacthed to it so that:
- A CO₂ absorber (e.g soda lime) is at the bottom
- Cotton wool is on top
- The organism(s) are on this
- The blob of coloured liquid is right at the start
- The 0cm mark of the ruler is lined up with the liquid
This is called a simple respirometer
You measure how far along the capilary tube the blob moves every so often
Distance moved ÷ time = rate of respiration
Alter the temperature to see how this affects the rate of respiration
This is your independant variable, so ensure you keep everythign else the same as they are your control variables
To set up a control experiment for this, you would have the same set-up with no organisms

Answer 141

A

An ecosystem is all the organisms and the habitat in which they live

Answer 142

A

All the organisms that live and interact in an ecosystem

Answer 143

A

The total amount of one species in a population

Answer 144

A

When organisms depend on each other for resources within an ecosystem.

Answer 145

A

Population size

=

(total size of area where organism lives ÷ total area of quadrats) x

number of organisms in all quadrats

Answer 146

A

Much is transferred to plant biomass. The rest is transferred to the environment by heating during the life processes.

Answer 147

A

Other organisms can’t use it.

Answer 148

A

Only some of the energy from the PC’s diet is converted to biomass and the rest is wasted by transferring to heat in the surroundings.
Therefore to get the same amount of energy, the SC will need to eat more.
This is why there is a limit to the size of a food chain.

Answer 149

A

It reduces significantly.

Answer 150

A

At each level more energy is being wasted so at each level there is less energy to be used and less biomass can be produced.

Answer 151

A

Since there is less biomass at each level, after a certain level, the amount of the lower species you’d have to consume would be too high.

Answer 152

A

Where organisms can be found in a food chain

Answer 153

A

A non-living factor that affects organisms

Answer 154

A

Abundance of Water
Light intensity
Temperature
Wind
Pollutants

Answer 155

A

An organisms adaptations.
If an adaptation is specific to a condition then an abiotic factor that affects that condition will mean that the organism is not longer adapted to their conditions

Answer 156

A

Use CP book for revision

[Will add before real exam]

Answer 157

A

The organisms in an ecosystem that affect each other.

Answer 158

A

Competition
Predation

Answer 159

A

When a predator eats their prey the population of prey decreases.
Now there isn’t enough food for the predator so their population decreases
Now that there is less predation, the prey’s population can increase again
Now there is more food for the predator so their population can increase again.
This goes on and so the predator is affected slightly after the prey

Answer 160

A

In an ecosystem with more biodiversity, a predator doesn’t prey on one species and a prey isn’t predated by one species.
This means that it is unlikely that one species will ever cause another’s population to decrease and if so, this wouldn’t affect the other species.

Answer 161

A

New species provide more habitats and/or food for many species.
For example in yellowstone when wolves were (re)introduced, this decreased elk numbers increasing beavers and increasing the amount of dams which altogether promoted the biodiversity of the ecosystem

Answer 162

A

High levels of pollution:
- Sludgeworm
- Bloodworm
Low levels of pollution:
- Stonefly nymph
- Dragonfly nymph

Answer 163

A

Lower levels of sulfur:
- Blackspot fungus on roses
Higher levels of sulfur:
- Lichens such as Lecanora conizaeoides

Answer 164

A

Trees provide habitats and food for many species.
More trees is an effective way of making an ecosystem suitable for more species.

Answer 165

A

They don’t give numerical/quantitative results and so aren’t fully accurate and comparable especially as both air and water pollution can be numerically measured.

Answer 166

A

An organism in a feeding relationship with another organism usually harmful to that other organism. e.g Lice and tapeworms

Answer 167

A

An organism in a realtionship with another organism which is beneficial to both as they each provide something to each other. (e.g. bees and flowers or oxpecker and zebras)

_{V̶e̶n̶o̶m̶ ̶i̶s̶ ̶a̶ ̶f̶i̶c̶t̶i̶o̶n̶a̶l̶ ̶c̶h̶a̶r̶a̶c̶t̶e̶r̶ ̶a̶p̶p̶e̶a̶r̶i̶n̶g̶ ̶i̶n̶ ̶A̶m̶e̶r̶i̶c̶a̶n̶ ̶c̶o̶m̶i̶c̶ ̶b̶o̶o̶k̶s̶ ̶p̶u̶b̶l̶i̶s̶h̶e̶d̶ ̶b̶y̶ ̶M̶a̶r̶v̶e̶l̶ ̶C̶o̶m̶i̶c̶s̶,̶ ̶c̶o̶m̶m̶o̶n̶l̶y̶ ̶i̶n̶ ̶a̶s̶s̶o̶c̶i̶a̶t̶i̶o̶n̶ ̶w̶i̶t̶h̶ ̶S̶p̶i̶d̶e̶r̶-̶M̶a̶n̶.̶ ̶T̶h̶e̶ ̶c̶h̶a̶r̶a̶c̶t̶e̶r̶ ̶i̶s̶ ̶a̶ ̶s̶e̶n̶t̶i̶e̶n̶t̶ ̶a̶l̶i̶e̶n̶ ̶S̶y̶m̶b̶i̶o̶t̶e̶ ̶w̶i̶t̶h̶ ̶a̶n̶ ̶a̶m̶o̶r̶p̶h̶o̶u̶s̶,̶ ̶l̶i̶q̶u̶i̶d̶-̶l̶i̶k̶e̶ ̶f̶o̶r̶m̶,̶ ̶w̶h̶o̶ ̶r̶e̶q̶u̶i̶r̶e̶s̶ ̶a̶ ̶h̶o̶s̶t̶,̶ ̶u̶s̶u̶a̶l̶l̶y̶ ̶h̶u̶m̶a̶n̶,̶ ̶t̶o̶ ̶b̶o̶n̶d̶ ̶w̶i̶t̶h̶ ̶f̶o̶r̶ ̶i̶t̶s̶ ̶s̶u̶r̶v̶i̶v̶a̶l̶.̶}

Answer 168

A

About 17% of the world’s protein consumption is fish based.
However overfishing leads to loss of certain fish species.
So the solution is to farm fish.
Since so many fish are kept in a small space, all their uneaten food and faeces sink to the bottom creating a harmful atmosphere alowing parasites and disease to spread easily throughout fish.

Answer 169

A

After humans have added new species to an ecosystem, these species may outcompete native species for resources meaning the native species reduce in numbers affecting the ecosystem.

Answer 170

A

Fertiliser is added
Heavy rain washes fertilisers off dissolving nitrates and phosphates into soil water
If plants take up the nitrates and phosphates and there is still some remaining this gets washed into streams and rivers
The high concentration of fertilising substances encourages rapid growth of algae and plants on water surface
Surface plants block sunlight and so plants in the water die as they stop photosynthesising
The decomposing bacteria increases in numbers and consumes more oxygen
Oxygen concentration in water decreases
Aquatic animals die due to anoxic water

Answer 171

A

Pros:

Ensure they’re safe
Provide them with all needed resources meaning other organisms can’t outcompete them

Cons:

They may become habitualised
Inbreeding may be required causing many genetic problems

Answer 172

A

Many organisms are interdependant and all the organisms play an important role in each other’s survival
Areas with larger biodiversity have a greater chance of recovering form natural disasters as not every organism will be affected
As humans we require plants and animals for many thing (e.g medicine) and so it is important that we preserve all the species we can for when our needs change

Answer 173

A

To ensure that species don’t become extinct

Answer 174

A

Having access to sufficient safe and healthy food at all times.

Answer 175

A

Wealthier people tend to want:

More food
More meat and fish produce in their diet

^{_{Good thing I’m dirt poor I gueabhfdlbhsl vjl lnsk}}

Answer 176

A

The amount of fertiliser used has increased as to increase the yield of crops.
However the process to create fertilisers release carbon dioxide.
Additionally, eutrophication can be a problem.

Answer 177

A

Climate change can move pests and pathogens into new areas.
For example if there is a pest that is a vector for a disease but the pest can only survive in warm conditions, as climate change increases the global temperature, they can go to more places.

Answer 178

A

The amount of land and energy taken up to farm and produce meat as a food product is much more than crops. 15 times more protein is produced from soy bean than animals in the same amount of land.

Answer 179

A

Pros:

Less CO2 emisison
Crops are easy to obtain

Cons:

Land could be used to grow food instead
May not be sustainable

Answer 180

A

Water evapourates from lakes and oceans to form water vapour
As water vapour rises it cools, condenses and forms clouds
Once cloud droplets get too large precipitaiton occurs
Some water runs off the surface directly into the lakes and rivers
Other water is percolated
some of this moves through rocks and soils till it reaches lakes and rivers
the rest is taken up by plants through transpiration and is evapourated directly

Answer 181

A

Solar stills
Nets
Distillation
Desalination in general. (obtaining pure water from salty water)
Treatment with chemicals and filteration

Answer 182

A

Plants respire and photsynthesise both releasing and taking in carbon
Animals feed off plants taking in carbon to their biomass and release it through respiration
When organisms die, their biomass is compressed into fossil fuels which release carbon through combustion
Soft tissue in the dead organism is eaten by decomposers which release carbon through respiration

Answer 183

A

They are made into carbon compounds like glucose. some may be used for growth as they are converted into biomass.

Answer 184

A

The carbon is taken in as carbohydrates fats and protiens in another organism and excreted through faeces.
Some may be digested and used as biomass in tissue

Answer 185

A

Nitrogen in the air is taken into the soil by nitrgoen fixing bacteria and by lightning
Or the opposite way round by breakdown of soil bacteria.
Plants absorb nitrates in the soil through their roots or through nitrogen fixing bacteria in root nodules
Animals feed on plants takin gin nitrogen
Death and excretion of animals means decomposers such a soil bacteria break down the protien and urea to soil nitrates

Answer 186

A

Nitrogen is used to from protiens and DNA and this allows organisms to grow.

Answer 187

A

Plants absorb nitrogen through the soluble substances taken up by their root hair cells, thus nitrogen must be in a soluble form to be absorbed by plants.

Answer 188

A

They maintain soil fertility by breaking down substances into nitrogen.

Answer 189

A

Spreading in manure around the field.The animal waste in this can be broken down to form nitrogen
Using fertilisers
Using plants that have root nodules and/or digging these roots in

Answer 190

A

They are parts of a plant that contain protected soil fixing bacteria which can produce soluble nitrogen compounds in the soil. (they are in a mutualistic relationship)

Answer 191

A

Rotating which crops are planted when in a ceratin area.
This means that the root nodules of one plant rotation make the soil more fertile and useful for the next crop planted increasing the next crop’s yield.

Answer 192

A

Reducing oxygen and water content as water and oxygen are needed for decomposers to respire and grow
Reducing temperature as this reduces the rate of reaction of decomposers
Irradiation of food packing as it kills decomposers

Answer 193

A

Well-decayed parts of waste garden material.
This is used to help crop fertility

Answer 194

A

Covered top to stop too mcuh rain from entering and too stop moisture and heat from leaving
Sides have openings to let oxygen in
This is as decomposers require both oxygen and water to respire and grow and higher temperature will increase rate of reaction
Compost heaps are turned every so often to ensure even decomposition

Answer 195

A

Loss of measure of decay ÷ the time taken

(e.g 6g lost in 3 days means 6 ÷ 3 = 2g/day)

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