S1 Biology Flashcards
1
Q
What is a microscope?
A
An instrument that makes small objects look larger
2
Q
What is resolution?
A
The ability to clearly distinguish two objects very close together as being separate
3
Q
How do you calculate magnification (M)?
A
Length of image (I) / Actual length (A)
4
Q
What is I ( Length of image )?
A
The size of a magnified object
I= M x A
5
Q
What is A ( Actual Length )?
A
The actual length of an object ( before magnification )
6
Q
What does an animal cell contain?
A
Nucleus, Cytoplasm, Cell membrane, Mitochondria
7
Q
What does a plant cell contain?
A
Nucleus, Cytoplasm, Cell membrane, Mitochondria, Cellulose cell wall, Vacuole, Chloroplasts
8
Q
What does a bacterial cell contain?
A
- Non-cellulose cell wall (peptitoglycan),
- Plasmids,
- Cytoplasm,
- Circular chromosome,
- Cell membrane
9
Q
What is the function of the cell membrane?
A
To allow the exchange of substances in and out of cells
(Through it’s selective permeability)
10
Q
What is the function of the cytoplasm?
A
Main part of the cell were all chemical reactions take place. Granular material
11
Q
What is the function of the nucleus?
A
Contains chromosomes which carry genes
Also
Controls the functions of a cell
12
Q
What is the function of the mitochondria?
A
Cellular respiration
13
Q
What is the function of the cell wall?
A
To protect and to provide support for the structure
14
Q
What is the function of the vacuole?
A
Contains cell sap that, when full, pushes the cell membrane into the cell wall making the cell more rigid, providing more support
15
Q
What is the function of the chloroplasts?
A
Contains chlorophyll which traps light, helping the plant to photosynthesise
16
Q
What are stem cells?
A
Cells that retain their ability to divide and differentiate into a wide variety of specialised cell types
17
Q
Where are stem cells found in animals?
A
In the umbilical cord or bone marrow
18
Q
Where are stem cells found in plants?
A
Meristems at the tip of the roots or shoots
19
Q
What are embryonic stem cells?
A
Stem cells that can differentiate into any kind of cell
20
Q
What are adult stem cells?
A
Cells that can only differentiate into a general cell type
21
Q
What are multicelled organisms?
A
Cells that can form specialised tissues, organs and organ systems
22
Q
What are the benefits of stem cell transplants?
A
It can treat diseases such as leukaemia and replace damaged body parts
23
Q
What are the risks of stem cell transplants? (4)
A
- Pre treatment can kill healthy cells as well,
- it can transfer viruses and diseases,
- and can sometimes lead to a formation of a tumour
- also the body can reject stem cells
24
Q
What is diffusion?
A
The random movement of molecules from a region of high concentration to a region of low concentration
25
What factors can affect the rate of diffusion? (3)
Temperature - The higher the temperature, the faster the rate of diffusion
Surface Area - The greater the surface area, the faster the rate of diffusion
Concentration *Gradient* - The greater the concentration gradient (difference) the greater the rate of diffusion
26
How many micrometres (μm) are in 1 millimetre (mm)
1000
27
How many millimetres (mm) are in 1 metre (m)
10000
28
What is 1 micrometre (μm)
10-3 mm -or- 10-6 m
29
Where does photosynthesis take place?
Chlorophyll in chloroplasts
30
What type of reaction is photosynthesis?
Endothermic
31
What is the word equation for photosynthesis?
Carbon dioxide + water -> glucose + oxygen
32
What is the balanced symbol equation for photosynthesis?
6CO2 + 6H20 --> C6H12O6 + 6O2
33
What is glucose used for in plants? (3)
- Respiration,
- Stored as starch,
- Converted to cellulose to make cell walls
34
How do you destarch a plant?
Keep the plant in a dark room for 24 - 48 hours
35
Explain how to conduct the starch test. (6)
- First, **destarch** the plant.
- Then keep the plant in bright light to photosynthesise.
- Take a leaf and place it in **boiling water** for 30 seconds to *kill the leaf*, stopping any chemical reactions.
- Then place the leaf in **boiling ethanol** to *remove chlorophyll* making the leaf brittle.
- Next, dip it back in the **water** to *soften* it.
- Finally, add **iodine** on to the leaf. If starch is present, the iodine will turn from **yellow-brown to blue-black**
36
What is a variegated leaf?
A leaf that only part of contains chlorophyll
37
How do you investigate the need for carbon dioxide? (5)
- A leaf from a destarched plant can be put into a conical flask with **sodium hydroxide** solution in it, to absorb all carbon dioxide.
- Put a **cotton ball soaked in sodium hydroxide** over the flask to stop any carbon dioxide getting in.
- Leave the leaf in **bright light to photosynthesise**.
- If no starch is present, then carbon dioxide is necessary for photosynthesis.
- For a control flask, do the same but with water in place of sodium hydroxide solution
38
How can you measure the rate of photosynthesis?
- By placing pondweed in an inverted funnel filled with water, with a bright light shining over it.
- Put an upside-down test tube over this and leave it for a certain period of time.
- Measure the volume of each bubble produced, and divide it by the time taken to get the rate of photosynthesis
39
What 3 factors affect the rate of photosynthesis?
- Light intensity,
- carbon dioxide concentration and
- temperature
40
What is a limiting factor? (**2**)
- An *environmental factor* that **limits the rate of reactions**
- due to that factor being **present** in **too small an amount**
41
What is the optimum?
The point at which the highest rate of a reaction is achieved
42
What is the **structure** of a **leaf**? (**5**)
- Waxy cuticle
- Upper epidermis
- Palisade mesophyll layer
- Spongy mesophyll layer
- Lower epidermis
43
What are the properties of the waxy cuticle?
Thin, Transparent to let light through, Prevents water-loss (waterproof)
44
How is the cross section of a leaf adapted for **light absorption**? (3)
- **Large surface area** of the **thin transparent cuticle**,
- presence of many tightly packed palisade mesophyll cells that are rich in chlorophyll and are *arranged perpendicularly*,
- thin so **short distance** for both **gases & light** to get to every cell
45
How is the cross section of a leaf adapted for **gas exchange**? (3)
- *Spongy mesophyll cells* have a **large surface area for gas exchange**,
- Intercellular spaces in the spongy mesophyll layer allow carbon dioxide and oxygen **easier entry and exit**,
- Stomata that allow *carbon dioxide* to **enter** the leaf and *oxygen* to **exit** the leaf
46
What are the properties of the upper epidermis?
No chloroplasts, quite transparent to allow light to pass through
47
What are the properties of the palisade mesophyll layer?
Packed with many chloroplasts, cells arranged vertically so more can fit in
48
What are the properties of the spongy mesophyll layer?
Contains intercellular air spaces, fewer chloroplasts than palisade mespphyll cells
49
What is the function of the stoma?
To allow gases to enter and exit
50
What is the function of guard cells?
To open and close the stomata at night
51
What is the compensation point?
The **light intensity** at which the rate of photosynthesis is equal to the rate of respiration
52
What solution is used in the experiment to calculate the compensation point of photosynthesis and respiration?
Hydrogen carbonate solution
53
What is the experiment to find the compensation point of photosynthesis and respiration? (8)
- Set up three test tubes containing water and **red hydrogen carbonate solution**.
- In the first one, place normal pondweed.
- In the second, place pondweed covered in lightproof foil,
- In the third, place partially shaded pondweed.
- Set up a bright light beside the test tubes and leave them for a period of time.
- In the first test tube, the hydrogen carbonate should turn from **red to purple** as the rate of photosynthesis is **higher** than respiration. (Less CO2)
- In the second it should turn from **red to yellow** as the rate of respiration is **higher** than photosynthesis. (More CO2)
- In the last, it should **stay red** as the rate of photosynthesis is equal to respiration (equal CO2)
54
What are biological molecules?
Molecules made and used by living organisms. Carbohydrates, proteins and fats
Only contain carbon, hydrogen and oxygen *(+ nitrogen in the case of proteins)*
55
What are the 7 nutrient groups?
Carbohydrates (both starch and small sugars), proteins, fats (or lipids), vitamins, minerals, water, fibre
56
What is a balanced diet?
A diet that includes all of the 7 nutrient groups in the right proportions
57
What are carbohydrates?
Sugars and starch such as glucose and lactose
58
What do we store carbohydrates as?
Glycogen
59
How many amino acids are there?
20
60
What do we use fats for?
Storing energy and providing insulation
61
What do we use carbohydrates for?
Energy
62
What do we use proteins for?
Growth and repair
63
What are proteins made up of?
**Long chains** of amino acids
64
What are carbohydrates broken down into?
Glucose
65
What are fats broken down into?
Fatty acids and glycerol
66
How do you test for fats?
Using the ethanol test
67
How do you test for protein?
Using the biuret test
68
How do you test for sugar?
Using Benedict's test
69
What is the biuret test?
**Sodium hydroxide** and **copper sulfate** mixed together. Changes from **blue to purple**
70
What is Benedict's test?
Add Benedict's solution to the food and **heat in a water bath**. Changes from **blue-black** to **brick red**
71
What is the test for lipids?
Mix the fat with ethanol to dissolve some of it, then **add it to water**. Changes from **clear to cloudy white**
72
How do you calculate the energy released in Joules?
Mass of water x Rise in water temperature x 4.2
73
What is the experiment for calculating the energy in food? (5)
- Hold a test tube in place suspended in the air, and fill it with 20cm3 of water.
- Measure the temperature of the water using a thermometer and record this temperature.
- Hold a piece of the food you are testing with a **mounted needle**, light it on fire using a bunsen burner and quickly hold it under the test tube.
- When the food has fully burned, or will not burn anymore, measure the temperature again.
- Calculate the temperature difference and use the equation to measure the energy released
74
What is an enzyme?
A **protein** that acts as a **biological catalyst**
75
What is a biological catalyst?
An enzyme that speeds up the rate of reactions in living organisms
76
What is an enzyme's active site?
The spot where the substrate fits perfectly into, and gets broken up
77
What does it mean that an enzyme's active site and the substrate are complimentary?
That the shape of the substrate fits perfectly into the active site of an enzyme
78
What is **enzyme specifity**? (**3**)
- Each enzyme is specific and **will only work** on **its normal substrate**
- As its **active site** is **complementary** to the **substrate**
- Forms an **enzyme-substrate complex**
79
What are the substrate and products of carbohydrase?
Carbohydrates --> Glucose
80
What are the substrate and products of amylase?
Starch --> Glucose
81
What are the substrate and products of protease?
Protein --> Amino acids
82
What are the substrate and products of lipase?
Fat --> Glycerol & fatty acids
83
How does temperature affect enzyme activity? (4)
- As the temperature increases, so does the chemical and kinetic energy of the enzymes so there is more enzyme activity and collisions
- until the optimum temperature,
- after which enzyme activity will slow due to enzyme denaturation,
- eventually ceasing completely
84
What is enzyme denaturation and how does it occur?
Above the optimum temperature (or both above and below it’s optimum pH) for enzyme activity, the enzyme's active site will undergo an irreversible change that results in the substrate no longer fitting into the active site
85
How does pH affect enzyme activity? (3)
- At an enzyme’s **optimum pH**, the activity of the enzyme is at it’s **greatest rate**,
- however if the pH **increases or decreases**,
- enzyme activity **decreases** (Due to enzyme denaturation)
86
How do you investigate the effect of temperature on enzyme activity?
In the case of the starch test:
- Set up different water baths at regular intervals of temperature and fill a number of test tubes with 5cm3 of starch,
- and the same number of test tubes with 5cm3 of amylase.
- Place them both in the water bath at the same time and wait until they reach the right temperature.
- Set up a spotting tile with a drop of iodine solution in each.
- Mix the 2 solutions together in a small beaker and quickly take a sample and place it in a dimple in the tile.
- Repeat this step at regular intervals until the iodine no longer turns blue-black.
- Repeat this for all the different temperatures
At whichever temperature it takes the least amount of time for a colour change to occur, the enzyme activity is at it’s fastest rate
87
What are the colour changes in hydrogen carbonate indicator?
- *Red* in **atmospheric levels** of CO2 (0.04%)
- *Purple* **below** atmospheric levels of CO2
- *yellow* **above** atmospheric levels of CO2
88
What is the definition of **Digestion**? (**2**)
- The breakdown of **large, complex, insoluble** molecules into **smaller, simple and soluble** molecules
- due to **enzyme action**
89
What are thermostable enzymes? Where are they found?
Enzymes which work at a wide range of temperatures without becoming denatured
Usually found in commercial products like **bio washing powder**
90
How is the structure of the ileum adapted for absorbing the products of digestion? (6)
- it is long (~3 meters long)/is folded/contains villi/contains microvilli
- it has a large surface area
- it has a good blood supply
- it maintains a diffusion gradient
- it has **thin/permeable membranes**
- it has a **short diffusion pathway**
- the lacteal
- absorbs fats/fatty acids and glycerol and returns them to the blood later
All are needed for full marks (1 of each with /)
91
What is the shape of a graph displaying the effect of concentration on **enzyme activity?** (**3**)
- The enzyme activity increases as enzyme activity **increases**,
- until a certain point when **other factors become limiting** *(e.g. substrate concentration)*
- and the graph **levels off**
92
What is the word and symbol equation for **aerobic** respiration in humans?
Glucose + Oxygen --> Carbon Dioxide + water + energy
C6H12O6 + 6O2 --> 6CO2 + 6H2O + energy
93
What is the word equation for **anaerobic** respiration in human muscles?
Glucose --> lactic acid + energy
94
What is the word equation for **anaerobic** respiration in yeast?
Glucose --> Alcohol + Carbon dioxide + energy
95
What do the different cells in the body use the energy released in respiration for? (5)
- Movement,
- growth,
- reproduction,
- active transport and
- heat
96
Is respiration an exothermic or endothermic reaction?
Exothermic because it releases energy
97
How do you investigate the effect of **temperature** on the respiration of yeast?
- Mix **3g of yeast with 4g of glucose with 100cm3** of **boiled and cooled** water in a beaker
- Leave at **room temperature** for an **hour**
- Fill a small test tube with this mixture
- Place a boiling tube upside down over the small test tube and quickly invert both tubes
- Place the tubes in a water bath at a temperature of **10°C**
- Measure the height of the bubble at the top of the inner, small tube
- Repeat at **various temperatures**
- After 30 minutes, measure the height of the bubble at the top of each of the inner tubes and calculate the change in height
98
Explain the steps involved in the experiment **demonstrating anaerobic respiration in yeast**
- a solution of glucose is first boiled to remove any dissolved oxygen and to sterilise it
- yeast cells are added to this solution only after it has cooled
- the solution of glucose with yeast is then placed in the apparatus
- a layer of oil must be added above the solution to prevent oxygen entering
- have a tube linking the test tube with another test tube containing limewater
- if the test tube turns milky, CO2 is present and anaerobic respiration has occured
99
How is energy used in the body?
- growth and repair
- reproduction
- active transport
- movement
- production of heat (for homeostasis)
100
How do you investigate the effect of **different sugars** on the respiration of yeast? (8)
- Mix **3g of yeast with 4g of glucose with 100cm3 of water** in a beaker
- Leave at **room temperature** for an **hour**
- Fill a small test tube with this mixture
- Place a boiling tube upside down over the small test tube and quickly invert both tubes
- Place the tubes in a water bath at a temperature of **30°C**
- Measure the height of the bubble at the top of the inner, small tube
- Repeat with **different sugars**
- After 30 minutes, measure the height of the bubble at the top of each of the inner tubes and calculate the change in height
101
Name each part of the pathway in the **respiratory system**
- trachea
- bronchi
- bronchioles
- alveoli
102
Why do the trachea and bronchi contain **rings of cartilage**?
To prevent each collapsing
103
What is the name given to the layer of muscle separating the lung from the abdomen?
The diaphragm
104
Where are **pleural membranes** located and what is their function?
- The outer part of the lungs
- they prevent friction between the lungs and rib cage
105
What is contained within **pleural membranes**?
Pleural fluid
106
What is between each of the rib bones
Intercostal muscles
107
How are alveoli adapted for respiration? (6)
- very large surface area (due to **millions** being in each lung)
- the cells are **moist** between alveoli and capillaries (making them **permeable**)
- only **two layers** of cells between alveolus and blood, making **diffusion distance very short**
- *good blood supply* **increases surface area** for diffusion while **maintaining high diffusion gradient**
- blood returning to lungs is *low in oxygen and high in carbon dioxide*, **increasing diffusion gradient**
- **diffusion gradients maintained by breathing** (removing carbon dioxide and bringing oxygen in)
108
What are the main respiratory surfaces in plants?
Spongy mesophyll cells
109
How are spongy mesophyll cells adapted for respiration? (2)
- there are lots of cells in contact with the air spaces, creating a **large surface area**
- their cell membranes are **thin, moist and permeable**
110
Explain the process of breathing in animals.
(Inhaling)
- intercostal muscles **contract** causing the ribs to move **up and out**
- diaphragm **contracts** and **moves down**
- the **volume** of the thorax **increases** and the **pressure** inside **decreases**
- air **enters** the lungs
(Exhaling)
- intercostal muscles **relax** and **move down and in**
- diaphragm **relaxes** and returns to it’s domed shape **(up)**
- **volume** of the thorax **decreases** and the **pressure** inside **increases**
- air **leaves** the lungs
111
What is the name given to the time taken for the breathing rate to return to normal?
Recovery time/rate
112
How would a fit person’s breathing rate compare with an unfit person’s?
They (fit person) would have:
- a **lower resting** breathing rate
- a **slower rate of increase** in breathing rate during exercise
- a **lower maximum** breathing rate
- a **faster recovery** rate
113
Explain the effect of exercise on breathing (4)
- exercise requires the movement of muscle cells which requires energy, **this is increased during exercise**
- aerobic respiration requires oxygen, therefore as more energy is used by the body, more air is inhaled
- this means more CO2 in the bloodstream, which means more air must be inhaled and exhaled to remove it
- the person will breathe with increased speed and depth to inhale more air and subsequently oxygen for aerobic respiration
114
Where is the respiratory system located in the body?
The **Thorax** (The chest cavity)
115
What is the thorax surrounded by?
**Ribs** of bone with **intercostal muscles** between them
116
What is the structure below the thorax?
The diaphragm, a muscular sheet that can move up and down
117
Where does air enter the body and where does it go?
Air enters through the nasal cavity where it is warmed and filtered before continuing into the lungs via the trachea
118
Where does gas exchange take place in humans?
The alveoli
119
What is the diaphragm represented by in the bell jar lung model?
A rubber sheet
120
What is the thorax represented by in the bell jar lung model?
The bell jar
121
What are the lungs represented by in the bell jar lung model?
Balloons
122
Explain how the bell jar lung model demonstrates the process of breathing
Inhaling
- As the rubber sheet (diaphragm) moves down, the volume inside the jar increases.
- This causes the pressure inside the jar to decrease and as a result, air enters the balloons (lungs) until the pressures inside and outside the jar are equal.
Exhaling
- As the rubber sheet (diaphragm) moves up, the volume inside the jar decreases.
- This causes the pressure inside the jar to increase and as a result, air exits the balloons (lungs) until the pressures inside and outside the jar are equal.
123
How does the bell jar lung model fail to accurately represent how breathing takes place in humans? **(2)**
- There is no representation of the ribs moving up and out for inhaling and down and in for exhaling.
- The thorax is much smaller in reality than in the bell jar lung model
- the diaphragm is, in actuality a domed shape before contracting, becoming straight
124
What is a **stimulus**?
Anything that we respond to/triggers an impulse
125
What does an effector affect?
A **receptor**
126
What happens when a **receptor** is stimulated?
It causes an **effector** to produce a **response**
127
What are receptors and effectors connected by?
A **coordinator**, usually the **brain** but may also be the **spinal cord**
128
What are the **brain** and **spinal cord** known as?
The **central nervous system**
129
What links the receptors and effectors to the coordinators?
Nerve cells or **neurones**
130
What do neurones carry information as?
Small electrical charges called **nerve impulses**
131
How are neurones adapted? (3/4)
(+ - They have a **nucleus** that controls the activities of the neurone)
- They have **long axons** so that nerve impulses can be carried across long distances throughout the body
- They have a fatty layer called the **myelin sheath** that acts as an insulator that helps to speed up the nerve impulses
- The **branched ends** of the axon allow the neurone to make junctions with other nerve cells
132
What is a synapse?
The junction between two neurones
133
How are nerve impulses transferred from one neurone to another? (4)
- When an electrical impulse reaches the end of the axon, it causes **(synaptic) vesicles** to release a special chemical called the **transmitter substance/neurotransmitter**
- which diffuses across the synapse to the neurone **adjacent**.
- If the concentration of transmitter substance is high enough on the other side of the synapse, it triggers an electrical impulse on the axon leaving the junction
- and the nerve impulse continues on its way
134
What is a voluntary action?
An action we do deliberately that involves conscious thought
135
What is a reflex action?
An action that does not involve conscious thought that happens automatically, like breathing or blinking
136
What are the two main characteristics of a reflex action?
They occur:
- very rapidly and
- do not involve conscious control
137
What makes reflex actions so rapid?
In a reflex pathway, the length of the pathway is kept as short as possible with the minimum number of neurones needed and as few synapses as possible
138
What is a reflex arc?
The nerve pathway involved in a reflex action
139
What is the **sensory neurone**?
The neurone that carries information from receptors
140
What is the **motor neurone**?
The neurone that carries information **from the spinal cord back to the effector**, causing a response
141
What is the **association / connector / relay** neurone?
The neurone that connects the sensory and motor neurone
142
What does the iris do?
Controls how much light enters the eye
143
What is the pupil?
The space in the iris through which light passes
144
What is the cornea?
The transparent front part of the eye that allows light to enter the eye and causes some refraction
145
What is the aqueous humour?
The transparent, incompressible watery liquid that helps focussing and to maintain the eye's shape
146
What is the conjunctiva?
The thin, transparent, protective outer covering of the eye
147
What is the retina?
The inner coat of the eye where light-sensitive cells are found
148
What is the lens?
The transparent, dome shaped part of the eye which refracts light onto the retina
149
What is the vitreous humour?
Jelly-like substance that helps maintain the shape of the eye and keeps the retina against the wall of the eye
150
What is the optic nerve?
Nerve that contains neurones carrying information to the brain
151
Where is the blind spot?
Where the optic nerve creates a gap in the retina
152
What is the suspensory ligament?
Ring of strong fibres supporting the lens that stretch and slack to allow different amounts of light to enter the eye
153
What are the ciliary muscles?
Ring of muscles that pull on the suspensory ligament to change the shape of the lens and allow different amounts of light into the eye
154
How does the eye focus on a distant object?
The ring of ciliary muscles relaxes, suspensory ligaments stretch and the lens is thin
155
How does the eye focus on a nearby object?
- The ring of ciliary muscles contracts,
- suspensory ligaments slack
- and the lens is thick
156
Why is controlling the amount of light entering the eye important?
If too little or too much light enters the eye and reaches the retina, it can damage the sensitive light receptor cells in the retina
157
What happens to the pupil in dim light?
The size of the pupil is increased to allow more light to enter the eye
158
What happens to the pupil in bright light?
The size of the pupil is decreased to restrict the amount of light entering the eye
159
What is negative feedback?
**Negative feedback** is a homeostatic mechanism in which conditions are **returned** to the **ideal or set point** **after** conditions have **deviated** from this set point
160
What does insulin do to blood glucose concentration?
It limits the concentration
161
Where is insulin produced and released?
The pancreas
162
What causes insulin to be produced?
In response to increasing or high blood glucose concentrations
163
What does insulin achieve?
The prevention on the concentration of glucose in the blood becoming too high
164
Why does the concentration of glucose in the blood need to be limited?
Too much glucose can damage body cells due to water loss
165
What is the main target organ for insulin and why?
The main target organ for insulin is the **liver** where it causes:
-- **Increased absorption** of glucose from the blood, reducing blood glucose concentration;
-- The conversion of excess glucose into **glycogen** which is stored in the liver
-- **Increased respiration**
166
What is a hormone?
A chemical message produced by special glands which release them into the blood
167
What is the organ that a hormone affects called?
The **target organ**
168
What is **homeostasis**?
Keeping the body in a constant state in response to changes outside and inside the body
169
What is **osmoregulation**?
A homeostatic process that controls the amount of water in the blood and other body fluids
170
What is diabetes?
A condition in which the body does not produce enough insulin to keep the blood glucose at the normal concentration
171
What 3 ways does the body gain water?
- Drinking liquids
- in food
- water as a product from respiration
172
How does the body lose water?
- evaporation of sweat
- breathing out water vapour
- in urine
173
Give the steps taken by the body when blood is **too dilute**
- blood concentration normal
- large drink of liquid
- *blood too dilute*
- kidney **reabsorbs less water** back into blood and **more urine** is produced **(LESS ADH)**
174
Give the steps taken by the body when blood is **too concentrated**
- blood concentration normal
- lots of water lost (eg sweat during exercise)
- *blood too concentrated*
- kidney **reabsorbs more water** back into blood and **less urine** is produced **(MORE ADH)**
175
What is ADH? Where is it produced and what is it’s target organ?
ADH (anti diuretic hormone) is a hormone which controls how much water the kidney reabsorbs
It is produced in the **brain** and it targets the **kidneys**
176
What blood vessel supplies the kidney?
What blood vessel exits the kidney?
- The renal artery (supplies blood for filtering)
- the renal vein (returns filtered blood to the vena cava)
177
Name each part of the kidney (at this level obvs)
Also
Name the other parts of the excretory system
- renal pelvis
- medulla (middle part of the kidney)
- cortex (outer part of kidney)
Other parts of excretory system
- ureter (tube to bladder)
- bladder
- sphincter muscle (holds urine in bladder)
- urethra (take urine out of the body)
178
What is phototropism?
The growth response by plants in which they grow in the direction of light
179
Why does phototropism occur?
and
how does it work?
Phototropism occurs when a plant receives light from one direction (**unilateral**)
It works as **auxin** (a hormone) is released from the **tip** of the plant and travels **disproportionately** to the **shaded part** of the plant (it travels in such a way **due to the direction from which the tip receives light**).
**More auxin** is on the shaded part of the plant, causing the plant to **grow more on this side** and therefore, bend toward light
180
Give **one** similarity and **one** difference between human and plant stem cells (2)
Similarity:
cells divide/mitosis/differentiate;
Difference:
plant stem cells can redifferentiate;
human stem cells cannot redifferentiate;
181
Why are stem cells useful in medicine? (2)
- ability to divide
- to produce cells of one/same type
182
What is the **function** of the **lacteal**? (**2**)
- **Absorbs breakdown products** of **lipids** (glycerol and fatty acids)
- and **returns** them *to the blood* **later**
183
What is **calcium** used for in plants?
Helps produce **cellulose** for **structural support**
184
What is **magnesium** used for in plants?
Helps produce **chlorophyll**
185
What are **nitrates** used for in plants?
Production of **proteins**
