Biology Paper Two Flashcards
(114 cards)
1
Q
What is Homeostasis?
A
Homeostasis is the maintenance of a constant internal environment.
2
Q
What happens if a stimulus is too high?
A
- Receptors detect a stimulus is too high.
- The coordination centre receives and processes the information, then organises a response.
- Effector produces a response which counteracts the change and restores the optimum level.
- The effectors will continue to produce the response for as long as they’re needed.
3
Q
What is the nervous system?
A
- CNS (Central Nervous System)
- Sensory neurones
- Motor neurones
- Effectors
4
Q
What are sensory neurones?
A
The neurones that carry information as electrical impulses from the receptors.
5
Q
What are motor neurones?
A
The neurones that carry electrical impulses from the CNS to effectors.
6
Q
What are effectors?
A
Muscles and glands which respond to nervous impulses.
7
Q
What are synapses?
A
Connection between two neurones. The nerve signal is transferred by chemicals which diffuse across the gap.
8
Q
What are the 4 parts of the brain?
A
Cerebral Cortex: outer wrinkly bit, it’s responsible for things like consciousness, intelligence, memory and language.
Medulla: Controls unconscious activities e.g breathing and heartbeat.
Cerebellum: Responsible for muscle coordination.
Spinal Cord
9
Q
What are ways that scientists study the brain?
A
- Studying patients with brain damage
- Electrically stimulating the brain
- MRI Scans
10
Q
What is the Sclera, Cornea and Iris?
A
Sclera: the tough, supporting wall of the eye.
Cornea: the transparent outer layer at the front of the eye, it refracts light into the eye.
Iris: contains muscle that allow it to control the diameter of the pupil, therefore how much light enters the eye.
11
Q
What is the Lens, Retina, Ciliary Muscles and Suspensory Ligaments?
A
Lens: focuses the light onto the retina
Retina: contains rods and cones
Ciliary and Suspensory Ligaments control the shape of the lens.
12
Q
What are the 4 stages of the menstrual cycle?
A
Stage 1: Day 1 - Menstruation starts, the uterus lining breaks down.
Stage 2: The uterus builds up again, from day 4 - 14.
Stage 3: An egg develops and is released from the ovary at day 14, this is called ovulation.
Stage 4: The wall is maintained and cycle restarts if no egg is fertilised.
13
Q
What is FSH?
A
Follicle-Stimulating Hormone
- Produced in the pituitary gland.
- Causes an egg to mature in one of the ovaries, in a structure called a follicide.
- Stimulates the ovaries to produce oestrogen.
14
Q
What is oestrogen?
A
- Produced in the ovaries.
- Causes the lining of the uterus to grow.
- Stimulates the release of LH and inhibits the release of FSH.
15
Q
What is LH?
A
Luteinising Hormone
- Produced by the pituitary gland.
- Stimulates the release of an egg.
16
Q
What is progesterone?
A
- Produced in the ovaries by the remains of the follicle.
- Maintains the lining of the uterus in the second half of the cycle.
- Inhibits the release of LH and FSH
17
Q
What is the plant hormone that controls growth?
A
Auxin.
18
Q
What is DNA?
A
Deoxyribonucleic acid.
- Contains coded information
- Found in the nucleus, in chromosomes
19
Q
What is a gene?
A
A gene is a small section of DNA found on a chromosome.
Each gene codes for a particular sequence of amino acids, which are put together to make a specific protein.
20
Q
What is a genome?
A
The entire set of genetic material in an organism.
21
Q
What is mRNA?
A
Proteins are made in ribosomes. They use a molecule called mRNA from DNA to code for these proteins.
22
Q
What are the different functions of proteins?
A
Enzymes
Hormones
Structural Proteins
23
Q
What is meiosis?
A
Produces cells which have half the normal number of chromosomes. 4 gametes are produced.
24
Q
What is cystic fibrosis?
A
A genetic disorder. It produces sticky mucus in air passages.
- It’s a recessive allele carried by 1 in 25.
25
What is polydactyly?
A genetic disorder where a baby is born with extra fingers of toes.
- Dominant allele.
26
What are the pros and cons of Embryonic Screening?
+ It will stop people suffering.
+ Costs the government.
+ There are laws to stop it going too far.
- Could increase prejudice.
- May come a point where everyone wants to screen their baby.
- Expensive.
27
What is selective breeding?
When humans artificially select the plants or animals that are going to breed so that the genes for particular characteristics remain in the population.
28
How can plants be cloned?
Tissue Culture:
- A few plant cells are put in a growth medium with hormones. They grow into clones of the parent plant.
- These plants can be made very quickly.
- Tissue culture is used by scientists to preserve rare plants that are hard to reproduce.
Cuttings:
- Take cuttings of good plants and then plant them to produce identical ones.
- Quick and cheap.
- Older and simpler method.
29
What is adult cell cloning?
1. Adult cell cloning involves taking an unfertilised egg cell and removing its nucleus.
2. The nucleus is then removed from an adult body cell and inserted into the empty egg cell.
3. The egg is then stimulated by an electric shock, this makes it divide.
4. When the embryo is a ball of cells, it's implanted into the womb of an adult female.
30
How are fossils formed?
From gradual replacement by minerals:
1. Things that don't decay easily (e.g bones) last a long time while buried.
2. They are eventually replaced by minerals as they decay. Which forms a rock-like substance.
3. The surrounding sediments also turn to rock but the fossil stays distinct.
Form casts and impressions:
1. When an organism is buried in a soft material. This then hardens around it. This leaves a cast around itself.
From preservation in places where no decay happens:
1. In amber and tar pits there is no oxygen or moisture so decay microbes can't survive.
2. In glaciers it's too cold for the decay microbes to work.
3. Peat bogs are too acidic for decay microbes.
31
What is speciation?
The development of a new species.
This occurs when populations of the same species become so different that they can no longer successfully interbreed to produce fertile offspring.
32
What is natural selection?
1. Isolation is where populations of a species are separated.
2. Isolation can happen due to a physical barrier e.g floods and earthquakes.
3. Conditions on either side of the barrier will be slightly different e.g different climates.
4. Because the environment is different on each side, different characteristics will become more common in each population.
5. Eventually the individuals from the different populations will have changed so much that they won't be able to breed.
33
How can bacteria evolve and become antibiotic-resistant?
1. Some bacteria can develop random mutations in their DNA. This can lead to them becoming resistant to a particular antibiotic. This leads to antibiotic-resistant strains.
2. These then reproduce rapidly.
3. This increases the amount of resistant bacteria.
4. This is easily spread.
5. MRSA is a common superbug.
34
What is classification?
Organising living organisms into groups.
35
What are the different classifications? (7)
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
36
Define a Herbivore.
Primary consumers that eat plants/algae.
37
What is a Tertiary consumer?
Carnivores that eat other carnivores.
38
What is an apex predator?
Predatorial carnivores that themselves do not have any predators.
39
What does a decomposer do?
Secretes enzymes into the environment by breaking down dead matter.
40
What is coral bleaching and when does it occur?
When coral polyps expel algae that lives inside their tissues.
41
What causes coral bleaching?
Warmer water temperature.
42
What relationship is crucial in order to maintain the health of a reef?
Symbiotic relationship between coral and algae.
43
What causes water temp to rise? (5)
```
Global warming.
Run off (dilution).
Pollution.
Over exposure to sunlight.
Extreme low tides.
```
44
Name an alternative to monoculture.
Crop rotation.
45
What is crop rotation?
Different crops being planted each year in the same field.
46
What advantages are there for crop rotation? (2)
Less damaging to soil.
| Less encouragement of pests.
47
What is monoculture?
Sustained growth of one crop at a time, where the farmer specialises in one product only. This makes it more efficient.
48
What is usually grown during monoculture? (2)
Fruits and veg.
| Cereals (wheat) and barley.
49
Name a disadvantage of monoculture?
Over time it can lead to nutrient deficient soil as well as pests.
50
What is a community?
A diverse group of organisms that exist together in the same place.
51
What is biomass?
Biological mass.
52
What is a population?
All individuals of one species in a given area.
53
State the biotic factors. (4)
Food availability.
New pathogens.
New predators.
Competition between species.
54
State the abiotic factors. (7)
```
Light intensity.
Soil PH.
Wind intensity.
Oxygen availability.
CO2 availability.
Temperature.
Moisture levels.
```
55
What is biodiversity?
A range of different species in a habitat.
56
Examples of a low biodiversity. (3)
Tundra.
A field.
Certain desserts.
57
Examples of a high biodiversity. (4)
Rainforests.
Jungle.
Forest.
Ocean.
58
What threatens/reduces biodiversity? (8)
```
Pollution.
Introduced species.
Increased farming.
Over exploitation.
Hunting/food.
Deforestation.
Global warming.
Climate change.
```
59
Name the benefits of biodiversity. (4)
Ecological services.
Industrial materials.
Medicine.
80% of our food comes from just 20 plants.
60
What happens if an animal goes extinct?
A domino effect is caused and population becomes too large without a predator.
61
What happens to the eco-system if an animal goes extinct?
The eco-system is strained. It is unable to provide enough food and water for the growing population.
62
What eventually happens to the population if an animal goes extinct?
It falls again (returns to normal).
63
What is food security?
Having enough food/nutrients to sustain the population.
64
Define symbiotic?
Organisms that live together and support each other.
65
What is a keystone species?
An organism who's presence controls everything in the eco system.
66
Name an example of a keystone species?
Sea stars.
| Elephants.
67
How does peat effect the amount of carbon in the atmosphere?
Peat is a 'carbon sink' so its able to trap and remove carbon from its natural cycle. Therefore levels decrease.
68
Why is deforestation occuring? (2)
Growing crops for bio-fuels.
| Providing land for cattle and rice fields.
69
What is a carbon sink?
A place where carbon is trapped and removed from the carbon cycle.
70
What is peat?
Partially decomposed plant tissue.
71
How does peat form?
The bacteria responsible for the last portion of decomposition is aerobic, because of the wet conditions Oxygen is unable to reach the tissue and Peat is formed.
72
Who benefits from decay of organic matter? (6)
```
Soil.
People (Farmers)
Animals.
Plants *extremely vital
Insects.
Predators.
```
73
Where do plants access their nitrogen?
From the atmosphere.
74
What does natural fertiliser contain?
Nutrients essential for growth such as carbon and nitrogen compounds.
75
Where does a quaternary consumer (apex predator) sit in the food chain?
Final organism in the feeding relationship.
76
What do quaternary consumers eat?
Only the tertiary consumer sits below it in the food chain, otherwise it is at the very top.
77
What is a trophic level?
A stage in a feeding relationship.
78
What does a trophic level represent? (2)
An organism in a food chain.
| A group of organisms in a food web.
79
What human activities lead to waste and pollution? (5)
```
Deforestation.
Burning fossil fuels.
Production of plastics.
Disposal of used materials.
Agriculture.
```
80
Is there a positive correlation between human population growth and the amount of waste and pollution being produced?
Yes
81
At what temp do enzymes denature?
Above 40 degrees.
82
What is the optimal temp for enzymes?
25 - 40 degrees.
83
What cycles is the decomposition cycle essential in? (2)
Nitrogen and carbon cycles.
84
What is decomposition?
Materials within oxygen matter being returned to the environment for use by other organisms.
85
What has the ability to change the rate of decomposition based on the population of decomposers being altered? (3)
Oxygen.
Moisture.
Warmth.
86
What is a reflex?
Reflex: a rapid, automatic responses that are unconscious.
87
What's a reflex arc?
- Neurons in the reflex arc go through the spinal cord or an unconscious part of the brain.
- When a stimulus is detected by receptors, impulses are sent along to a sensory neuron to the CNS.
- When the impulses reach the synapse between the sensory neuron and a relay neurone, they trigger chemicals to be released.
- When the impulses reach a synapse between a relay neuron and a motor neuron. Chemicals are released again.
- These then travel to an effector.
- The muscle contracts and moves
88
How does the iris reflex?
When the receptors detect very bright light, a reflex is triggered that makes the pupil smaller. The circular muscles in the iris contract and the radial muscles relax. This reduces the amount of light that can enter the eye.
89
How do we look at close objects?
1. Ciliary muscles contract, which slackens the suspensory ligaments.
2. The lens becomes more curved.
3. This increases the amount by which it refracts light.
90
How do we look at distant objects?
1. Ciliary muscles relax, which pulls the suspensory ligaments tight.
2. This makes the lens go thin.
3. So it refracts light by a smaller amount.
91
How do we treat long-sightedness?
1, This occurs when the lens is the wrong shape and doesn't refract the light enough or the eyeball is too short.
2. The images of near objects are brought into focus behind the retina.
3. You can use glasses with a convex lens
4. The lens refracts the light rays so they focus on the retina.
This is called hyperopia
92
How do we treat short-sightedness?
1. This occurs when the lens is the wrong shape and refracts the light too much or the eyeball is too long.
2. The images of distant objects are brought into focus in front of the retina.
3. You can use glasses with a concave lens to correct it.
This is called myopia.
93
What are the treatments for vision defects?
- Contact lenses
- Laser eye surgery
- Replacement lens surgery
94
What happens when we are too hot?
- Hairs lie flat
- Sweat is produced
- Blood vessels dilate so more blood flows close to the surface.
95
What happens when we are too cold?
- Hairs stand up, to trap an insulating layer of air
- No sweat is produced
- Vasoconstriction
- Shiver
96
A patient with a brain tumour is experiencing difficulties with language and memory.
Which area of brain is most likely to be affected by this tumour?
Cerebral cortex
97
A patient's doctor has concerns about operating to remove the tumour.
Suggest 2 possible concerns the doctor may have about possible effects on the brain?
- Physical damage to the brain
| - Increased problems with brain fuctions
98
The eye adjusts its shape slightly to focus light.
| Describe how the eye adjusts to focus on distant objects?
The ciliary muscles relax allowing the suspensory ligaments to pull tight which results in the lens becoming thinner/less rounded.
99
Presbyopia is a condition in which the lens of the eye become less elastic and isn't easily able to form a rounded shape.
Suggest how having presbyopia will affect a person's vision.
If the lens cannot form a rounded shape, light from nearby objects won't be refracted enough to be focused on the retina. This means people with presbyopia will be unable to focus on nearby objects
100
What's the difference between nerves and hormones?
```
Nerves:
- Very fast action
- Act for a very short time
- Act on a very precise area
Hormones:
- Slower action
- Act for a long time
- Act in a more general
```
101
What happens when glucose levels are too high?
- Blood with too much glucose
- Insulin in secreted by the pancreas.
- The insulin makes liver turn glucose into glycogen.
- Glucose moves from blood into liver and muscles cells.
- Blood glucose reduced.
102
What is type 1 diabetes?
1. Where the pancreas produces little or no insulin.
2. This means blood glucose levels can rise and kill a person.
3. Injections of insulin are needed throughout the day. This is to make sure that glucose is removed from the blood quickly.
4. The amount of insulin that needs to be injected depends on the person's diet and how active they are.
5. They also need to limit the intake of food rich in simple carbohydrates.
103
What is type 2 diabetes?
1. This is where someone becomes resistant to their own insulin, they produce it but their body cells don't respond properly.
2. This can also cause a person's blood sugar level to rise.
3. Being overweight can increase your chance of developing type 2 diabetes.
4. Eating a carbohydrate-controlled diet or regular exercise.
104
What substances are removed from the body in urine?
1. Urea
2. Ions
3. Water
105
A runner went for a 10 mile run on a warm day. When she got home she noticed that her urine was darker than normal. Explain why she produced darker coloured urine.
As the runner ran, she sweated, resulting in water loss, and less water in the blood.
Receptors in her brain detected this decrease.
The coordination centre receives this information and coordinated a response by the pituitary gland.
The pituitary gland releases ADH into the blood.
The ADH causes the kidneys to reabsorb more water, resulting in less water being released in the runners urine.
So her urine is more concentrated and therefore more darker.
106
Explain why the patient does not lose glucose from her blood during dialysis?
The dialysis fluid contains the same concentration of glucose as healthy blood, so there is no concentration gradient and no net movement of glucose.
107
Give a disadvantage of kidney transplants?
- Long waiting lists for transplants
| - Risk it will be rejected
108
Explain how the dialysis machine removes urea from the patient's blood?
The urea diffuses our through the dialysis membrane into the dialysis fluid., because the concentration of urea in the blood is higher than in the dialysis fluid.
109
What are the 4 stages of the menstrual cycle?
Stage 1 - Day 1, uterus lining breaks down for about 4 days
Stage 2 - Day 4-14 lining builds up again.
Stage 3 - Day 14, an egg develops and is released
Stage 4 - Day 14-28 wall is maintained.
110
How can hormones be used to reduce fertility?
Oestrogen can be used to prevent the release of an egg
| Progesterone produces a thick mucus which prevents the sperm reaching an egg
111
What is IVF?
Collecting eggs from the women's ovaries and fertilised in a lab using a man's sperm.
The fertilised eggs are then grown into embryos in a lab incubator.
Once the embryos are tiny balls of cells, one of two are transferred into the women's uterus to improve chance of pregnancy.
112
What are the pros and cons of IVF?
+ Give an infertile couple a child
- Multiple births can happen, higher risk of miscarriage, stillbirth
- Success rate is low 26%
- Emotionally and physically stressful
113
What is adrenaline?
A hormone released by the adrenal glands.
| Released in response to stressful or scary situations.
114
What is thyroxine?
Thyroxine regulates metabolism and is released by the thyroid gland.
Also stimulates protein synthesis for growth and development.
A negative feedback system keeps the amount of thyroxine in the blood at the right level.
