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Biology GCSE Revision > Paper 2 > Flashcards

Paper 2 Flashcards

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1
Q

What is homeostasis?

A

Controlling the conditions inside the body, like water content, ion content, body temperature, and blood glucose concentrations.

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2
Q

What is the endocrine system?

A

Collection of glands that produce hormones.

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3
Q

What is the path for the nervous system?

A

Stimulus-Receptor-Coordinator (CNS)-Effector
Reflex Arc:
Stimulus-Receptor-Sensory neurone-Relay neurone-Motor neurone-Effector-Responce

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4
Q

What are synapses?

A

Junction between neurones. The electrical impulses travel by chemicals at the end of one neurone and diffuse across the gap to complementary gaps in the other neurone.

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5
Q

What is myopia?

A

Short sightedness

  • Image is focused in front of retina
  • Caused by a long eyeball, or the lens being too curved
  • Corrected by concave lens
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6
Q

What is hyperopia?

A

Long sightedness

  • Image is formed behind the retina
  • Caused by a short eyeball, or the lens being too flat
  • Corrected by convex lens
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7
Q

What are some components of the eye?

A

Retina-contains rod cells and cone cells
Optic Nerve- carries impulses from retina to brain
Sclera- tough, white, protective layer
Cornea- refracts light, bends it as it enters the eye
Iris- sets of muscles that controls the size of the pupil and regulates light reaching retina
Cillary muscles and suspensory ligaments- C.M changes the thickness of lens while focusing. S.L holds lens in place

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8
Q

What are some parts of the brain?

A

Cerebral Cortex- Consciousness, memory, intelligence
Cerebellum- Muscular activity and balance
Medulla- Unconscious activities, like heartbeat, breathing, and movement of gut.

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9
Q

What are some of the glands in the body, and what do they produce?

A

Thyroid gland) controls metabolic rate
Pancreas) controls level of glucose in blood
Testes) production of sperm
Ovaries) menstrual cycle
Adrenal glands) controls adrenaline
Pituitary gland) stimulates thyroid gland to make thyroxine, stimulates ovaries to release eggs and oestrogen, stimulates testes to make testosterone and sperm.

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10
Q

What happens if glucose levels in the blood start to rise?

A

Insulin produced by the pancreas causes glucose to change into glycogen. The insulin makes the liver store glucose.

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11
Q

What happens if glucose levels in the blood start to fall?

A

The pancreas realises glucagon to make the liver break down its stores of glycogen and convert it back into glucose.

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12
Q

What are the stages of the menstrual cycle?

A

1) Pituitary gland releases FSH
2) FSH stimulates egg maturation and oestrogen release
3) The ovaries release oestrogen.
4) The pituitary gland releases LH
5) Oestrogen switches off FSH and stimulated LH release
6) LH stimulates egg release
7) Oestrogen causes the uterus lining to thicken
8) Egg is unfertilised, period occurs

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13
Q

What is phototropism?

A

When the auxins (plant hormones) elongate towards a stimulus, in this case, light. Shoots grow towards the light, while the roots have no reaction to light

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14
Q

What is geotropism?

A

The effect of gravity on the growth of plants. Shoots grow away from gravity, meaning it is negative geotropism. Roots grow towards gravity, meaning it is positive geotropism.

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15
Q

What is hydrotropism?

A

When the auxins are affected by water. Some species of roots grow towards water, meaning it is positive hydrotropism.

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16
Q

How are plant hormones used?

A

Auxins) weed killers, rooting powders, in tissue culture
Ethene) control fruit ripening
Gibberellins) increase fruit size, promote flowering, end seed dormancy.

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17
Q

How is body temperature controlled?

A

By the thermoregulatory centre in the brain, picked up by the receptors that monitor temperature of the blood

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18
Q

What happens to conserve heat when the body temperature is too low?

A
  • Blood vessels constrict to reduce the flow of blood, which reduces energy transferred by radiation (vasoconstriction)
  • Sweat production stops, reduces energy transferred to surroundings
  • Skeletal muscles contract and relax rapidly, causing you to shiver, which causes exothermic, which is exothermic.
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19
Q

What happens when body temperature is too high?

A
  • Blood vessels dilate, lets more blood flow from capillaries, more energy is transferred to surroundings by radiation (vasodilation)
  • Produces more sweat to evaporate and cool the skin
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20
Q

What is the role of the kidneys?

A

The kidneys filter glucose, mineral ions, urea, and water out of the blood.

  • mineral ions, urea, and water are turned into urine (depending on amount of water in the blood)
  • Water and mineral ions are reabsorbed depending on the needs of the body (selective reabsorption)
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21
Q

What happens if there’s too much water in the blood?

A

1) Pituitary gland realises less ADH
2) Kidney tubules absorbs less water
3) Urine becomes less concentrated, more diluted, paler in colour. Water levels return to normal.

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22
Q

What happens if there’s too little water in the blood?

A

1) Pituitary gland realises more ADH
2) Kidney tubules reabsorb more water back into the blood
3) Urine becomes more concentrated, darker in colour. Water levels return to normal.

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23
Q

What is dialysis, and when is it needed?

A

It’s an artificial kidney, for people with kidney failure.
-Dialysis fluid contains no urea, meaning it can diffuse across and out of the blood.
-Glucose isn’t lost, as concentration of glucose in the blood and in the machine are the same.
Disadvantages) have a strict diet, hospital for hours multiple times a week

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24
Q

What are some advantages of having a kidney transplant?

A

A transplant means less of the restrictions. While they do have to take immunosuppressants, they have eat a normal diet and generally lead a normal life.

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25
Q

What is mitosis?

A

It results in genetically identical cells, the two daughter cells are clones of the parent. It takes place in all cells, except gametes. Generally occurs during growth and repair.

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26
Q

What is meiosis?

A

Occurs during the production of gametes and takes place in reproductive organs. It produces four gametes, the daughter cells have half as many chromosomes as the parent. They’re genetically different from each other and the parent cell.

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27
Q

What’s the general structure of DNA?

A

Double helix. Backbone is made of sugar phosphate. the 4 bases are held together with a hydrogen bond contains the code.

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28
Q

What are the base pairs in DNA?

A

C-G
A-T
thymins, adenines, guanines, cytosines

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29
Q

What is the gene for being female?

A

XX

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30
Q

What’s the gene for being male?

A

XY

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31
Q

How are proteins made?

A

Three bases code for each amino acid in a protein (called a triplet code) Each group of 3 DNA bases is the code for a different amino acid.

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32
Q

What is an allele?

A

Alleles are different forms of the same gene, sometimes referred to as variants.
-e.g) the gene may be eye colour, so the alleles might be blue, brown, or green.

33
Q

What is a phenotype?

A

The physical appearance or biochemistry of an individual for a particular characteristic
-eg) the eye colour brown is the phenotype, as it’s visible

34
Q

What’s a genotype?

A

The alleles present.

35
Q

What does heterozygous mean?

A

The characteristic that has different alleles.

36
Q

What does homozygous mean?

A

Characteristic with two identical alleles.

37
Q

Why is controlling gene expression important?

A

The body doesn’t want every cell making every protein at once, there need to be specialised cells for making certain proteins when needed.

38
Q

What is the purpose of non-coding DNA?

A

Non-coding areas of DNA are involved in switching genes on (so they’re expressed) and off (so they’re not expressed). They can also switch only part of a gene on so a different protein is expressed.

39
Q

How does gene mutation change the production of proteins?

A

1) Causes a change in base sequence
2) Change in triplet code
3) Change in sequence of amino acids
4) Change in how it folds

40
Q

What changes can result from a mutation?

A

1) Enzymes almost unchanged- active site is the same shape, no change
2) Active site shape changes, so substrate isn’t complementary and doesn’t fit, the enzyme doesn’t work
3) Active site changed shape, so a different substrate fits. Catalyses a different reaction.

41
Q

What are some advantages and disadvantages of screening for genetic disorders?

A

Advantages) It provides a choice, if they want to get an abortion or not. Allows parents to prepare, emotionally and financially. Reduces number of people living with genetic disorder, reduces health care cost over time.

Disadvantages) Expensive. Encourages abortion. May lead to miscarriage. May cause harm to mother.

42
Q

What are some examples of genetic variation?

A

Eye colour, nose shape, sex, dimples.

43
Q

What are some examples of environmental variation?

A

Scars, diet, lifestyle. Characteristics that genes didn’t control.

44
Q

What are some examples of both genetic and environmental variation?

A

Height, weight, skin colour (sun and pigmentation)

45
Q

What do animals compete over?

A

Food, territory, and mates.

46
Q

What do plants compete over?

A

Light, space, water, and mineral ions.

47
Q

How are animals adapted?

A

Structural adaptations) eg, the shape or colour of the organism or a part of the organism
Behavioural adaptations) eg, migration to a beter climate, basking in the sun to warm
Functional Adaptations) {related to reproduction and metabolism} e.g., antifreeze in cells

48
Q

How are some animals adapted for cold climates?

A

The smaller the surface area to volume ratio, the easier it is to reduce the energy of energy

  • surface area of ears are small, to reduce energy loss
  • blubber and thick fur coats, as insulation
49
Q

How are some animals adapted to hot climates?

A
  • Very concentrated urine to limit water loss. Absorb water from food
  • Active at early morning and evening, when it’s cooler
  • Animals with thin and large ears transfer energy to the environment to keep cool
50
Q

What are some adaptations in plants?

A
  • Plants in dry conditions have leaves with a small surface area, to reduce water loss
  • desert plants have large rot systems to absorb as much water as they can
  • Desert plants store water in their tissues
  • Plants growing in the shade may have big leaves with a bigger surface area to absorb as much light as they can
51
Q

What was Jean-Baptiste Larmark’s theory considering evolution?

A

Changes that occur in an organism during its lifetime can be passed onto it’s offspring

52
Q

What was Charles Darwin’s theory considering evolution?

A

Natural selection. Adaptations are inherited from parents with genetic advantages.
(Alfred Wallace agreed with Darwin, encouraged him to publish his findings)

53
Q

Why did people originally reject Darwin’s theory?

A
  • Religious conflict, went against creation story
  • Insufficient evidence
  • He could’t explain variation, and how it was inherited, because of the lack of knowledge considering genetics.
54
Q

What’s a species?

A

A group of organisms that reproduce to produce fertile offspring.

55
Q

What is speciation?

A

Speciation is where the populations become so genetically different, they can’t reproduce to produce fertile young. Caused by:
-isolation, genetic variation between the populations, natural selection that differs between the two.

56
Q

When can fossils be formed?

A
  • If parts of an organism haven’t decayed due to the lack of needed conditions for decay, like oxygen
  • Parts of an organism are replaced by minerals as they decay
  • Traces of organisms, like footprints, burrows, and root tracks are preserved
57
Q

How are fossils evidence of evolution?

A

They show how different organism have changed ver time. There are gaps in the knowledge of the past, because most organisms were soft-bodied and unlikely to leave fossils.

58
Q

What is extinction?

A

When there are no remaining individuals in a species alive.

59
Q

What might cause the extinction of a species?

A

Arrival of new predators, arrival of new pathogens, conditions changing, new competitors, disastrous events.

60
Q

What are the stages of selective breeding?

A

1) Choose parents from a mixed population that show the desired characteristics, and breed them together.
2) The offspring that show the desired characteristics are bred together
3) This continues over multiple generations, until all the offspring show the desired characteristics.

61
Q

What are some plant methods of cloning?

A

Tissue Culture) small groups of cell from one plant are placed in agar jelly, were they’re given nutrients and hormones to encourage the plant to grow into genetically-identical clone of the original plant.

Cuttings) A piece of the parent plant is removed, where it’s placed in soil and given hormones to encourage root growth. It’ll grow into a clone of the parent.

62
Q

How are animal cells cloned?

A

Embryo Transplant) Before the zygote becomes specialised, it is removed and split. Mitosis creates more cells as it forms into an embryo. The cells that had been removed are identical, and placed into surrogate mother.

Adult Cell Cloning) Nucleus from an adult body cell is inserted into an empty egg cell. An electric shock causes the e.g. cells to divide to make an embryo, where it’s then inserted into a surrogate.

63
Q

What are the steps for genetic engineering?

A

1) Choose desired characteristics
2) Isolation of the genes responsible for the characteristics
3) Insertion of gene into another organism’s DNA
4) Replication of the genetically modified organisms.

64
Q

How does bacteria produce insulin by genetic engineering?

A

The insulin gene from a human cell is inserted into the bacteria’s plasmid (ring of DNA) by an enzyme. The plasmid with the insulin gene is inserted into the bacteria, which then replicates many times. The insulin gene is switched on and the insulin in harvested.

65
Q

What are some benefits of genetic modification?

A
  • Insulin and growth hormones are mass produced, can help more people
  • Mice that mimic tumours can help further treatments
  • Larger yield of crops
  • High nutrition GM crops can reduce starvation and hunger.
66
Q

What are some of the concerns over genetic modification?

A
  • Long term effects aren’t clear
  • Concerns over effect of GM crops on health
  • Infertility genes from GM crops can spread to wild
  • Human engineering could lead to chosen characteristics and designed children
67
Q

What is classification?

A

The organisation of living things into groups according to their similarities. (helps scientist speak a common language and record the biodiversity)

68
Q

What is Carl Linnaeus’s hierarchical structure to classify organisms?

A

Kingdom, phylum, class, order, family, genus, species

69
Q

What are the three domains?

A

Archaea) primitive bacteria, like the extremophiles, who can live in extreme conditions
Bacteria) true bacteria and cyanobacteria (organism that can photosynthesis)
Eukaryota) Cells that contain a nucleus.

70
Q

How are food chains arranged?

A

1) Producer
2) Primary consumer
3) Secondary consumer
4) Tertiary consumer
5) Top level consumer

71
Q

What is the predator-prey relationship?

A

Prey population increases as predator population decreases

Prey population decreases as predator population increases

72
Q

How is biomass lost?

A

In faeces, and in waste products like carbon dioxide, glucose, and water in respiration, water and urea in urine.

73
Q

What are the conditions for decay?

A

Temperature, moisture, oxygen.

74
Q

What are some abiotic factors affecting communities?

A

Light intensity, temperature, moisture, soil pH, mineral concentration in soil, wind intensity and direction, oxygen, and carbon dioxide

75
Q

What are some biotic factors affecting communities?

A

Availability of food, new pathogens or parasites, predators, and new competitors.

76
Q

What are some features in intensive farming?

A
  • Limiting movement to limit energy loss, antibiotics to prevent spread of disease
  • High-protein food (fatten them up)
  • Temperature (keeps them warm, limits energy loss)
  • Light, vitamin D
77
Q

What is interdependence?

A

Each species depends on other species for food, shelter, pollination, etc. If one species os removed, it can affect the whole community.

78
Q

What’s a quadrat?

A

A square frame. Sample areas have to be random, to reflect true distribution.
-Use a random number generator to decide where to drop the quadrat
Find the mean. It’s quantitative sampling, easy to compare habitats.

79
Q

What’s a transect?

A

Not random.

  • Stretch a tape measure between two points, sample the organisms along the line at random intervals, using quadrats.
  • Shows the distribution along a line

Biology GCSE Revision (2 decks)

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