Biology Paper 2-Major Focus Of Exam Flashcards
(155 cards)
1
Q
What is homeostasis?
A
Regulation of internal body conditions
2
Q
What is your body temperature monitored and controlled by?
A
The brain
3
Q
What is the part of the brain that monitors and controls body temperature?
A
Thermoregulatory centre
4
Q
How can the thermoregulatory system control blood temperature?
A
It contains receptors which are sensitive to the temperature of the blood
5
Q
Besides the thermoregulatory centre containing receptors sensitive to blood, what is another way the thermoregulatory centre can control temperature?
A
The skin contains receptors, that send electrical impulses down sensory neurones to the thermoregulatory centre
6
Q
Give 3 ways that body temperature can be returned to normal when it has gone too high
A
Sweating
Flushing
Hairs lie flat
7
Q
How does sweating cool the body down?
A
Releases water on surface of the skin
Water evaporates, taking energy
8
Q
What is flushing a result of ?
A
Vasodilation of blood capillaries
9
Q
How does vasodilation of blood capillaries cool the body down?
A
More blood follows to surface of skin
Heat can transfer out of
Blood to surroundings
10
Q
Give 3 ways body temperature can be returned to normal when too low
A
Vasoconstriction
Shivering
Hairs stand up
11
Q
How does vasoconstriction warm the body up?
A
Less blood flow to surface of skin
Less heat lost to surroundings
12
Q
How does shivering warm the body up?
A
Causes our skeletal muscles to contract
Increases rate of respiration to generate needy for the contraction
Releases heat
13
Q
What is the control of body temperature an example of?
A
Homeostasis
14
Q
What are 2 comparisons of the nervous system and the endocrine system?
A
The nervous system is faster
The effects of the nervous system are more short lived
15
Q
What does the endocrine system consist of?
A
A number of glands
16
Q
What do glands secrete?
A
Hormones directly into the blood
17
Q
What is a hormone(3)
A
A chemical messenger that passes through the bloodstream to a target organ
18
Q
Besides the endocrine system have a slower, but more long-lasting effect, what’s another key difference between the NS and the ES?
A
The nervous system uses electrical impulses, whereas the endocrine system uses hormones
19
Q
What is the role of the pancreas?
A
Releases hormones- eg insulin - control blood glucose concentration
20
Q
What do the ovaries and testes release?
A
Hormones involved in puberty and reproduction
21
Q
What does the thyroid gland produce?
A
Hormones involved in growth and regulating the body’s basal metabolic rate
22
Q
What does the adrenal gland release?
A
The hormone adrenaline
23
Q
When is adrenaline produced?
A
In times of fear or stress
24
Q
Where is the pituitary gland located?
A
In the brain
25
What is another word for the pituitary gland?
The master gland
26
What does the pituitary gland release?
A number of different hormones depending on the conditions
27
What do pituitary hormones cause?
Other hormones to be released
28
What do pituitary hormones act on?
Other glands
29
When does the pancreas produce insulin?
After a meal, when blood glucose concentration is high
30
Where does insulin travel and what does it trigger?
Travels in the bloodstream
And triggers body cells to take up
Glucose
31
Besides triggering cells to
| Uptake glucose, what else can insulin trigger?
Liver and muscle cells to store excess glucose as glycogen
32
What is wrong with person with type 1 diabetes?
Their pancreas doesn’t produce enough insulin
33
What do people with type 1 diabetes do to counteract their problem?
Inject themselves with insulin
34
What’s wrong with people who have type 2 diabetes?
Cells stop responding to insulin
35
How can type 2 diabetes be treated?
A controlled carb diet
| Take exercise
36
What is a major risk factor for type 2 diabetes?
Obesity
37
If the blood glucose concentration is too low, what hormone does the pancreas release?
Glucagon
38
What does glucagon trigger?
Liver cells to convert glycogen back to glucose
39
In a graph of blood glucose concentration against time, what does the line fluctuate?
The balance between the releasing of insulin and glucagon
40
What type of cycle do insulin and insulin form?
Negative feedback
41
What are 3 ways we can lose water?
Exhaling
Sweat
Urination
42
What substances can sweat contain?
Sodium ion and urea
43
How is urea removed from the kidney?
Blood enters kidney through an artery
Contains urea
Kidney removes this and excess substances
Leave kidney as urine and store in bladder
44
How does the kidneys adjust the level of molecules in the blood?
Blood passes through capillaries
Small molecules filtered out- eg urea and water and glucose
Pass into tube
All of glucose, some water and ions are reabsorbed back into the blood
Urea, excess water and ions are excreted as urine
45
How do we deal with excess amino acids?
Liver breaks down the amino acids to produce ammonia
Desmond room
Ammonia is converted to urea and excreted
46
What hormone does the pituitary gland release when the level
| Of water in the blood falls?
ADH
47
What does ADH cause?
The kidney tubules to become more permeable to water
48
Increased ADH=
| Less____ produced
Urine
49
What does the ADH cause the kidneys to?
Reabsorb more water into the blood
50
If blood becomes too dilute, what does the pituitary gland stop releasing?
ADH
51
When the pituitary gland stops releasing ADH, is more or less
Water reabsorbed back in the blood by the kidneys?
Less
52
If a person has kidney failureX what will their blood contain?
A higher concentration of water, ions and urea
53
In kidney dialysis, where does the patients blood pass over?
A semi permeable membrane
54
What will the semi permeable membrane not allow through?
Large molecules like proteins
55
What’s on the other side of the semi permeable membrane?
Dialysis fluid
56
What does the dialysis fluid contain ?
Normal
| Concentration of water and ions, and no urea
57
Why does the urea diffuse from the blood into the dialysis fluid ?
Because of the concentration gradient
58
Why is the dialysis fluid constantly refreshed?
To
Maintain a steep
Concentration gradient
59
What’s some disadvantage of kidney dialysis?
Inconvenient- visit hospital regularly
| Controlled diet- low protein
60
What’s an alternative to kidney dialysis?
Kidney transplant
61
What is an advantage of dialysis?
No shortage of machines
62
What’s 2 advantages of a kidney transplant?
Allow for normal life
| Only expensive initially
63
What are 2 disadvantages of kidney transplants?
Shortage of donors
| Patients need to take anti rejection drugs for rest of their life
64
What is phototropism?
A response of a plant to light
65
How did scientists first suggest plant tips produced a hormone?
They removed the tips of shoots and found they didn’t grow towards the light
Then they put foil
Over the tip and found it didn’t grow towards the light either
66
What did scientists do to tell us that the lower parts of shoots aren’t sensitive to light?
They covered the lower parts of the shoot the shoot grew towards light
67
In shoots, what does auxin trigger?
Cell growth
68
Where does the light cause auxin to concentrate on?
The darker side of the shoot tip
69
Because of auxin, when plants are shone with light, does the darker side
Grow faster?
Yes
70
What do plant roots grow towards?
The force of gravity
71
What is gravitropism or geotropism?
Plant response to gravity
72
What does gravity cause the auxin to
| Do?
Concentrate on the lower side
73
In roots, does auxin promote
Or inhibit
Cell growth?
Inhibit
74
In the roots due to auxin, does the lower side grow faster or slower than the upper side?
Slower
75
What are giberellins
| Important for?
Seed germination
Flower
Production
76
What does Ethene control?
Cell division and ripening of fruits
77
What are producers important?
They are the source of biomass
78
What do scientists call molecules such as glucose?
Biomass
79
What type of consumer eats the producer?
Primary consumer
80
What type of consumers eat primary consumers?
Secondary consumers
81
What organisms eats a secondary consumer?
Tertiary consumer
82
What are predators?
Consumers that kill other animals
83
What’s the prey?
The animal being eaten
84
Describe the predator prey cycle using an example
```
Warm summer- lots of grass
More of rabbits offspring survive
Rabbit population increases
Fox population increases- more prey
Rabbit population falls- more predators
Fox population falls- less prey
Rabbit population increases- less predators
Cycle
```
85
What is the predator and prey cycle only true in ?
A stable community
86
What is a stable community?
A community where all biotic and abiotic factors are balanced
87
What a couple of examples of abiotic factors?
Wind direction
Temperature
Levels of moisture
88
What is random sampling used to compare?
Numbers of organisms in different areas
89
What do we use to carry out random sampling?
A quadrat
90
How do we use a quadrat?
Place it on the ground
| Count number of organisms inside it
91
In random sampling, where is the quadrat placed?
At random locations across the area - could use random numbers To select location
92
Describe how we can compare to areas, one with light conditions, one with dark conditions
Place quadrat randomly
Count number of organisms inside it
Move quadrat to different location
Count number of organisms
Repeat until we sample a large number of random locations
Dark conditions
Repeat the same steps and compare
93
Why do we place the quadrat down a large number of times ?
More likely to get valid results
94
Why don’t we use a quadrat in one area?
Won’t give sample that accurately represents the whole area
95
What’s the equation for total population size?
Total area/area sampled x number of organisms of specifies in sample
96
When do we use sampling along a transect?
How number of species change as we move across a habitat
97
What is a transect?
A line
98
How do we use a transect?
Place so it runs across the habitat
99
After placing the transect across the habitat, what do we do next?
Use a quadratic to count number of organisms at intervals on the transect
100
When using a transect and quadrats on sand dunes inland from the sea, how can we get valid results?
Repeat the whole process with the line shifting along
101
Describe how to measure the population size of a common species in a habitat
Use 2 tape measures to lay out an area(eg 10 by 10m)
Use a random number generator to create a set of co ordinates(4,5)
Count number of species within it
Record number and repeat none more times to get a 10 time sample
Estimate whole population using an equation
102
If we thinks there’s a big difference in the percentage of daisies within an area, what should we do?
Throw more quadrats- cover a higher percentage of the area
103
Describe how we use transects and quadrats to see how number of daisies changes from the tree outwards
Place tape measure at tree
Use quadrat to count daisies at start
Record light intensity - light meter
Move transect 1m down transect and repeat
104
How does carbon enter the carbon cycle?
By photosynthesis
105
How does carbon dioxide return back to the atmosphere?
By aerobic respiration
106
Describe the steps in the carbon cycle
```
CO2 in atmosphere
Plants gain it by photosynthesis
Return it by respiration
Organisms eat plants and gain carbon
They respire
Carbon in waste
Broken down by decomposerss
They respire- co2 returned
Combustion of fossil fuels- release
```
107
If decomposes can’t function effectively, what happens?
Carbon is dead remains is converted to fossil fuels
108
Why are decomposers important?
They cycle materials
Return co2 and release mineral
Ions
109
Describe the steps in the water cycle
Energy from sun causes water to evaporate from surface of the sea
Water vapour condenses in air, forming clouds
Transpiration and exhalation
Water in clouds fall as precipitation
Some water reevaporates, some
Passes in rocks to make aquifers
110
What role do organisms play in the water cycle?
Animals- exhalation
| Plants- transpiration
111
What are examples of decomposers?
Bacteria and fungi
112
What do gardeners use compost as natural fertilisers?
Compost is rich in minerals
113
What are some conditions for decomposers?
Temperature
Water
Oxygen
114
Why does decomposition take place at warmer temperatures?
Enzymes work faster
115
Why is compost usually quite warm?
Decomposers release energy when they respire
116
Why is it important that the compost isn’t too hot?
Enzymes in decomposers denature and die
117
Why do decomposers work faster if compost is moist?
Many chemical reactions in decay require water
118
Why is a plentiful supply of oxygen important for decomposers?
They carry out aerobic respiration
119
What’s an adaptation of compost bins?
Holes
120
Why do some compost bins have holes?
Allow oxygen in for decomposition
121
Why do gardeners mix up the compost?
Allow oxygen to distribute evenly
| Break up large clumps/ increase surface sea for decomposition
122
In the absence of oxygen, what do decomposers carry out?
Anaerobic decay
123
What does anaerobic decay mainly produce?
Methane- biogas
124
What are biogas generators used to provide?
Fuels for homes
125
Explain what goes wrong on the regulation of blood sugar levels in a person with type 1 diabetes
Pancreas produces little insulin
Liver is unable to remove glucose from blood
This causes levels to rise to a dangerous level
126
Hypopituitsrism is a condition in which the pituitary gland stops secreting hormones, why could people have certain symptoms of all are linked to low Thyroid hormone levels?
Pituitary gland releases hormones that act on other glands, directing them to release hormones
Oof a pituitary gland hormone that acts in the thyroid gland isn’t released, the thyroid gland may stop releasing hormones, causing the symptoms
127
Why after exercise does your urine go a dark colour?(6)
Sweat while running=water loss
Receptors in brain detect decreased water content in bloor
Coordination centre in brain receives this and coordinates a response- pituitary gland
Pituitary gland released ADH
ADH caused kidneys to reabsorbed more water, resulting in less water being released in urine
128
Explain how toxic waste substances are removed from the bloodstream during dialysis
There’s a partially permeable membrane between fluid and machine
Fluid contains normal conc of glucose and ions so glucose didn’t lost
Urea sissies into fluid and released into good then excreted
Protein molecules are too large so can’t diffuse
129
Describe the role of kidneys in selective reabsorption to produce urine
Kidneys act as filters and filter blood
All of glucose is selectively reabsorbed
Some water and ions are reabsorbed
Waste produces like excess water and urea are released through urine
130
What’s meant by a positive gravitropic response?
Plants grow upwards, against gravity
131
Explain how some of shoots from seedlings bend towards light
Unequal distribution of auxin
More aux in on darker side
Causes elongation of darker sode
132
Why does asexual reproduction lead to genetically identical offspring?
No mixing of genetic information as there’s no fusion of gamete’s
133
Similarities and differences between meiosis and mitosis
Mitosis- 1 parent, produces genetically identical offspring
Meiosis- 2 parents , produce variant offspring
Both involve the replication of dna
134
Describe the structure of dna
Polymer made up of repeating sun units
It’s 2 strands form a double helix structure
Consists of sequences of nucleotides
Nucleotides contains a sugar phosphate and base
T pairs with A and c with g as complementary base pairs
135
How can cystic fibrosis lead to damage if the lungs
Produces mucus
Trapped in respiratory pathways
Affects cell membranes and can lead to death
136
Why do many compost heaps have air holes?
Rate of decay is faster because it slows oxygen in so microorganisms can respire aerobically
137
Explain how carbon form desd organisms is recycled
Decomposers break down dead organic matter through the use of enzymes
As they respire aerobically, they releases carbon dioxide
This carbon dioxide is returned to atmosphere and absorbed by plants for photosynthetic
138
Similarities and differences between quadrats and transects
Both used with each other
Quadrats- used in random sampling to avoid bias+ count number of organisms in specific area
Transects- used in systematic sampling and show distribution in an area
139
Independent variable for required practical 8- effect of light on seedling
Conditions - light/dark
| Direction of light
140
Dependent variable for required practical 8
Mean height of seedlings
141
Control variables of seedling practical
Number of seeds
Temperature
Volume of water seedlings are given
142
What can you do to decide where you place your first quadrat?
Use a random number generator to generate a set of coordinates
143
Describe the negative feedback lol that takes place when blood glucose levels are too low
Stimulates pancreas to release glucagon
Causes glycogen in liver to be converted to glucose
Blood sugar Returns to normal
Glucagon no longer released
144
Explain how the brain is altered to changes in external temperature
Temperature reflected in skin and thermoregulatory centre has receptors that detects blood temp
Send impulse to brain
145
Suggest what effect replacing a cotton wool pad with a ball of cotton wall has
Hall is uneven so can change volume and distribution of water
146
Describe the plant hormones practical
Put cotton wool into 3 Petri dishes and add same vol of water
Add 10Seeds to each dish and place them in warm place
Allow seeds to germinate and add water if cotton wool dries out
Once seeds have germinated, ensure dishes contain same number of seeds
1 dish sits in full light , 1 sits in dark cupboard , 1 sits in partial light
Every day for a week, measure height of each seedling and record results
Calculate mean of seedlings each day and compare mean heights in different locations
147
State some control variables and how they can be controlled
Number of seeds- use same number of seeds in each dish and remove any if need be
Type of seeds- use seeds that come from same packet
Vol of water- use measuring cylinder to add same vol of water
Temperature- keep dishes in place where temp is stable
148
Explain why more water is lost by breathing during a race
More energy needed
More respiration
Increased breathing rate to supply oxygen
149
What’s the end 2 marks for the question explain how carbon is recyclables into the growth of new leaves ?
Glucose is produced in photosynthesis and used to make amino acids and proteins , required for growth of new leaves
150
Explain how can a mutation could cause the enzyme not to work
```
Changes from c to t- changes in bases
Changes amino acid
Change protein
Shape if active site changes
Enzyme no longer fits substrate
```
151
Disadvantage of factory farming
Disease spreads rapidly
| Antibiotics can build up on food chain
152
Explain how effiecincu of factor farming can be increased
Kept in temp controlled and restrict environment
Less energy lost in movement and less energy lost in regulating temp
More muscle
Mass
On each pig
153
Suggest what would happen in the body of a person that has a disorder due to an overactive thyroid gland
Too much thyroxine released into blood
Raises BMR
Increase in respiration
154
2 biological reasons why kidney transplant is better than dialysis
Blood ain’t in contact with machine, so lower risk of infection
Changes in concentrations of minerals are minimised , so less chance of causing damage to crlls
155
3 differences between mitosis and meiosis
Mitosis produces 2 daughter cells, whereas meiosis produces 4
One cell division in mitosis, but 2 in meiosis
Mitosis produces genetically identical offspring, meiosis produces variant
