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GCSE Biology (OCR Gateway) > B1 - Understanding Organisms > Flashcards

B1 - Understanding Organisms Flashcards

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1
Q

List factors that increase blood pressure:

A
  • Stress
  • Smoking
  • Being overweight
  • High alcohol intake
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2
Q

Explain the possible consequences of a high blood pressure.

A

Your blood is being pumped at a higher pressure, therefore blood vessels are more likely to burst - causing strokes, brain or kidney damage.

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3
Q

Explain the possible consequences of a low blood pressure.

A

Blood is not being pumped around the body as effectively, meaning your cells are not receiving oxygen and glucose. This can make you tired, especially if your brain isn’t receiving enough oxygen.

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4
Q

How does smoking increase the blood pressure?

A
  • Carbon monoxide reduces the oxygen-carrying capacity of red blood cells, meaning that the heart begins to pump blood at a faster rate to compensate.
  • Nicotine increases heart rate.
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5
Q

Explain how carbon monoxide reduces the oxygen-carrying capacity of the blood.

A

Carbon monoxide combines with the haemoglobin in red blood cells, which reduces the amount of oxygen they can carry.

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6
Q

How can your diet contribute to an increased risk of heart disease?

A
  • Saturated fats lead to a build up of cholesterol (plaque) in the arteries. This means that arteries become narrower, restricting the flow of the blood, possibly causing heart attacks.
  • Eating too much salt can elevate blood pressure.
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7
Q

Explain how narrowed coronary arteries, together

with a thrombosis, increase the risk of a heart attack.

A
  1. The heart muscle is supplied with blood by the coronary arteries.
  2. If these becomes narrowed, less blood can flow into the heart - meaning less oxygen is received.
  3. Blood flow can also be limited by thrombosis (blood clots).
  4. If the thrombosis blocks off an already narrow artery, it is possible for the blood (and oxygen) flow to be cut off completely.
  5. This causes a heart attack.
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8
Q

What two substances are fats made out of?

A

Fatty acids and glycerol.

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9
Q

How is digested food stored in the body?

A
  • Carbohydrates are stored in the liver as glycogen or converted into fats.
  • Fats are stored under the skin and around organs as adipose tissue.
  • Proteins are not stored.
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10
Q

Explain why vegetarians need to eat proteins from a
wide range of sources compared to people who eat
proteins of animal origin.

A

Some amino acids, called essential amino acids, need to be gained from your diet as they cannot be made by the body.

Animal proteins contain all of these essential proteins, whereas plant proteins only contain a fraction of them.

Therefore, vegetarians they digest the full spectrum of essential proteins.

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11
Q

List ways the human body is defended against pathogens:

A
  • Hydrochloric acid in the stomach kills pathogens.
  • Skin is a barrier.
  • Pathogens trapped by mucus in airways.
  • Blood clotting prevents entry of pathogens.
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12
Q

How do mosquitoes spread malaria?

A
  • They are vectors, meaning they carry the disease (protozoan) without getting it themselves.
  • The protozoan is a parasite that lives off its host.
  • The mosquito spreads the disease by feeding off a host infected with protozoan, and then taking that protozoan (in the form of blood) to another organism. By feeding on that second organism, the vector inserts the parasite (protozoan) into their blood vessels.
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13
Q

How can we use our knowledge of vectors to limit the spread of disease?

A
  • We know that mosquitoes lay their eggs in areas of water. We can drain these areas or spray them with insecticide.
  • Or, we can use fish to eat the mosquito larvae.
  • Furthermore, we can protect people from malaria by limiting their contact with mosquitoes. This can be achieved using insecticides or malaria nets.
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14
Q

What is a benign tumour?

A
  • Tumour grows until no more room.
  • The cells stay where they are.
  • Not usually dangerous.
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15
Q

What is a malignant tumour?

A
  • Tumour grows.
  • Spreads to other sites in the body.
  • Dangerous, often fatal.
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16
Q

How can you reduce your risk of developing cancer?

A
  • Not smoking to reduce risk of lung cancer.

- Eating less processed meat and more fibre to reduce risk of colon cancer.

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17
Q

How do pathogens cause symptoms of an infectious disease?

A
  • Damaging cells in the body.

- Releasing poisonous toxins.

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18
Q

List three processes that allow the immune system to deal with pathogens:

A
  • Consuming them (white blood cells engulf foreign cells)
  • Producing antitoxins
  • Producing antibodies
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19
Q

Describe how antibodies kill pathogens.

A
  1. Every pathogen has unique antigens.
  2. White blood cells detect foreign antigens, and start producing specific antibodies for that pathogen.
  3. Those specific antibodies can then be produced rapidly around the body to kill similar bacteria or viruses.
  4. Some white blood cells remain (memory cells) that are able to produce those specific antigens if that pathogen enters the body sometime in the future.
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20
Q

Explain the process of immunisation.

A
  1. It can take your body a long time to produce specific antibodies when it first encounters a new pathogen.
  2. It can take so long, that the symptoms might kill you first.
  3. Therefore, you can be immunised.
  4. Harmless, dead or inactive, pathogens are injected into the body. These pathogens have antigens.
  5. These antigens trigger an immune response, so the white blood cells start producing antibodies to attack.
  6. The white blood cells that remain (memory cells), are capable of producing antibodies immediately when a live/harmful form of that pathogen enters the body.
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21
Q

What is passive immunity?

A

You use antibodies made by another organism. It is only temporary.

e.g. antibodies are passed from mother to baby via breast milk.

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22
Q

What is active immunity?

A

The immune system is able to make its own antibodies after being stimulated by a pathogen. This includes becoming naturally immune, or artificially immune via vaccines.
- It’s usually permanent.

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23
Q

What are the advantages and disadvantages of immunisation?

A
  • Stops you from getting.
  • Stops disease from spreading.
  • Short-term side effects, e.g. swelling or redness.
  • Can’t be vaccinated if already ill as immune system is weakened.
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24
Q

What are the differences between antibiotics and antivirals?

A
  • Antibiotics kill bacteria without killing your body cells, but don’t kill viruses.
  • Antivirals stop viruses from reproducing.
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25
Q

Why do we need to use antibiotics carefully?

A

If we overuse antibiotics, the more resistant strains are able to develop and increase their resistance. As a result, the antibiotics can’t be used to treat infections.
e.g. MRSA - the hospital superbug

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26
Q

Why are double-blind trials used to test drugs?

A
  • Scientists and volunteers unaware of which drug is the placebo.
  • Removes all chance of bias.
27
Q

What is the function of the cornea?

A

Refracts light into the eye.

28
Q

What is the function of the iris?

A

Controls amount of light entering the pupil.

29
Q

What is the function of the lens?

A

Refracts light, focusses onto the retina.

30
Q

What is the function of the retina?

A

Light-sensitive, covered in receptors called rods and cones that detect light.

31
Q

What is the function of the optic nerve?

A

Carries impulses from the receptor to the brain.

32
Q

How does the eye focus light from distant objects?

A
  1. The ciliary muscle relaxes, allowing the suspensory ligaments to pull tight.
  2. This pulls the lens into a less rounded shape, so light is refracted less.
33
Q

How does the eye focus light from near objects?

A
  1. The ciliary muscle contracts, which allows the suspensory ligaments to relax/slacken.
  2. As a result, the lens becomes more rounded and the light is refracted more.
34
Q

Describe the basic pathway of light through the eyeball.

A
  • Refracted through cornea and lens.

- Brought into focus on retina.

35
Q

What causes someone to be long-sighted? How can this be corrected?

A
  1. The lens is the wrong shape or the eyeball is too short.
  2. As a result, light is focused behind the retina.
  3. Convex lenses to correct it.
36
Q

What causes someone to be short-sighted? How can this be corrected.

A
  1. Lens is wrong shape, or eyeball is too long, causing the light to bend/refract too much.
  2. As a result, light is brought into focus in front of the retina.
  3. Concave lenses to correct.
37
Q

How does binocular vision allow us to judge depth?

A
  1. Some animals have two eyes that work together, binocular vision.
  2. When you look at an object, your brain compares too images.
  3. The more similar the two images, the further away the object.
  4. Allows us to judge distances well, but we have a narrow field of vision.
38
Q

List the stages in a reflex arc.

A

stimulus → receptor → sensory
neurone → central nervous system → motor neurone
→ effector → response

39
Q

Explain how neurones are adapted to their function.

A
  • Branched endings (dendrites) meaning they can connect with lots of other neurones.
  • Sheath along the axon that acts as an electrical insulator, speeding up the electrical impulse.
  • They’re long (less connections needed, therefore impulses travel faster).
40
Q

Which part of the cell is an electrical impulse passed along?

A

Axon

41
Q

How does an electrical impulse pass through a synapse?

A
  • Synapse is a connection between two neurones.
  • Electrical impulse triggers release of transmitter chemicals that diffuse across the gap.
  • These chemicals bind to receptor molecules on the membrane of the next neurone.
42
Q

How do depressants effect the synapse?

A
  • Depressants bind with receptor molecules on the membrane of the neurone, blocking the electrical impulse. This decreases brain activity.
43
Q

How do stimulants effect the synapse?

A
  • Stimulants increase the amount of neurotransmitter released, causing more to travel across the synapse.
44
Q

Explain the cause of a smoker’s cough.

A
  • Smoking damages celia on the epithelial tissue.
  • Encourages mucus to be produced.
  • Cilia are damaged, so mucus can’t be cleared - instead, sticks to airways.
  • As a result of mucus along the airways, a smoker’s cough occurs.
45
Q

Describe how the liver becomes damaged as it removes alcohol.

A
  • Enzymes in liver break down alcohol.

- Toxic products of alcohol breakdown cause liver damage.

46
Q

How do vasoconstriction and vasodilation increase or reduce heat transfer to the environment?

A
  • Vasoconstriction: blood vessels near the surface constrict so that less heat is transferred to the surroundings.
  • Vasodilation: blood vessels widen close to the surface, meaning more blood is flowing near the surface, resulting in more heat radiating to the surroundings.
47
Q

How is body temperature controlled by the brain?

A
  • Thermoregulatory centre in brain.
  • Contains receptors that are sensitive to blood temperatures.
  • If high or low temperature detected, brain can send out electrical or hormonal impulses to keep homeostasis in the body.
48
Q

What is the difference between type 1 and type 2 diabetes?

A

Type 1 - Pancreas produces little or no insulin.

Type 2 - Body become resistant to insulin.

49
Q

Explain how insulin controls blood sugar levels.

A

If blood glucose levels are too high, more insulin is added to the bloodstream by the pancreas. As a result, the liver starts converting this glucose into glycogen.

If blood glucose levels are too low, insulin is not added. As a result, the liver begins converting glycogen into glucose.

50
Q

Why does the body take longer to respond to hormones than electrical impulses?

A

Electrical impulses travel much faster than hormone - hormones must travel via the blood.

51
Q

Where do auxins promote growth? Where do auxins inhibit growth?

A
  • Auxins promote growth in the shoot.

- Auxins inhibit growth in the root.

52
Q

Explain how auxins contribute to phototrophism?

A
  1. When a shoot tip is exposed to light, it accumulates more auxin on the side that’s in the shade than the side exposed to the light.
  2. This makes the cells grow (elongate) faster on the shaded side, resulting in bending toward the light.
53
Q

In terms of negative and positive trophism, describe the roots.

A

Roots are positively geotrophic (grow toward gravity), but negatively phototrophic (grow away from light).

54
Q

In terms of negative and positive trophism, describe the shoots of plants.

A

Shoots are positively phototrophic (grow toward light), but negatively geotrophic (grow away from gravity).

55
Q

Why might plant hormones be useful commercially?

A
  • Can be used to delay the ripening of the fruit, allowing the fruit to be picked for a longer period of time (remaining firm, reducing damage during transport/processing).
  • Hormones can force seeds to germinate, allowing farmers to grow crops all year round (many seeds will only naturally germinate at certain points in the year).
  • Hormones can disrupt growth patterns and be used to kill weeds.
56
Q

If you are homozygous for a trait, you…

A

…have two alleles of the same for that particular gene (e.g. CC or cc).

57
Q

If you’re heterozygous for a trait, you…

A

…have two different alleles for that particular gene (e.g. Cc).

58
Q

Explain gamete formation.

A
  1. Body cells are made up from 23 pairs of chromosomes (46 chromosomes in total).
  2. When these cells split to form gametes, the chromosomes are also split up.
  3. Therefore, gametes are left with half the number of chromosomes (23).
  4. In each gamete, some of your father’s chromosomes are grouped with chromosomes from your mother.
  5. This random shuffling of chromosomes leads to variation.
59
Q

Explain how fertilisation leads to mutations.

A
  1. Two random gametes join together.

2. The random nature leads to variation.

60
Q

How do mutations lead to variation?

A

Occasionally, a gene might mutate.

This leads to new characteristics, increasing variation.

61
Q

Describe how sex (in mammals) is determined by sex

chromosomes.

A

Male - XY chromosomes

Female - XX chromosomes

62
Q

How do auxins move around in a plant?

A

Auxins are dissolved in a solution.

63
Q

How do our bodies monitor and control blood temperature?

A

The hypothalamus in our brain detects changes in our blood temperature, and respond by either releasing hormones or an electrical impulse. This response causes some kind of temperature control mechanism to occur (e.g. vasoconstriction), allowing our body to keep our blood temperatures stable.

This type of response to control blood temperature is an example of NEGATIVE FEEDBACK.

GCSE Biology (OCR Gateway) (6 decks)

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