(Paper 2) 5.6 Homeostasis: Higher Tier content

Question 1

What is accommodation in the eye?

Answer 1

The process of changing the shape of the lens to focus on near or distant objects.

Question 2

What happens to the lens when focusing on a near object?

Answer 2

It becomes thicker to refract light more strongly.

Question 3

What happens to the lens when focusing on a distant object?

Answer 3

It becomes thinner to refract light slightly.

Question 4

What do the ciliary muscles do when focusing on a near object?

Answer 4

They contract.

Question 5

What do the suspensory ligaments do when focusing on a near object?

Answer 5

They slacken (loosen).

Question 6

What is the lens shape when viewing a near object?

Answer 6

Fat/thicker.

Question 7

What is the muscle tension on the lens when viewing a near object?

Answer 7

Low

Question 8

What do the ciliary muscles do when focusing on a distant object?

Answer 8

They relax.

Question 9

What do the suspensory ligaments do when focusing on a distant object?

Answer 9

They are stretched/tight.

Question 10

What is the lens shape when viewing a distant object?

Answer 10

Thin.

Question 11

What is the muscle tension on the lens when viewing a distant object?

Answer 11

High.

Question 12

Why does the lens need to refract light strongly for near objects?

Answer 12

Because light rays from near objects diverge more and need more bending to focus on the retina.

Question 13

What are three examples of conditions controlled by homeostasis?

Answer 13

Water concentration, temperature, and glucose concentration.

Question 14

What is a negative feedback mechanism?

Answer 14

A control system that reverses a change to return conditions back to the set point.

Question 15

What happens if a condition in the body rises above the set point?

Answer 15

Control systems reduce it to return to the set point.

Question 16

What happens if a condition in the body falls below the set point?

Answer 16

Control systems increase it to return to the set point.

Question 17

What are the general stages in negative feedback?

Answer 17

Conditions change from the set point

Change is detected

Corrective mechanisms activated

Conditions return to set point

Corrective mechanisms switched off

Question 18

What is an example of a negative feedback mechanism in the body?

Answer 18

Body temperature control – sweating when hot, shivering when cold.

Question 19

Which part of the brain controls body temperature?

Answer 19

The hypothalamus.

Question 20

What gland produces thyroxine?

Answer 20

The thyroid gland.

Question 21

What does thyroxine do?

Answer 21

It stimulates the basal metabolic rate and controls how quickly oxygen and food are used to release energy.

Question 22

What other roles does thyroxine play in the body?

Answer 22

It is important for growth and development.

Question 23

How are thyroxine levels in the blood controlled?

Answer 23

By negative feedback.

Question 24

What happens when thyroxine levels are low in the blood?

Answer 24

Hypothalamus releases TRH

TRH stimulates pituitary gland to release TSH

TSH causes thyroid to release more thyroxine

Thyroxine levels return to normal

Question 25

What happens when thyroxine levels are normal or high?

Answer 25

TRH release is inhibited by the hypothalamus TSH release is inhibited by the pituitary gland This prevents thyroxine levels from rising further

Question 26

What gland produces adrenaline?

Answer 26

The adrenal glands.

Question 27

When is adrenaline released?

Answer 27

In times of fear or stress.

Question 28

Is adrenaline controlled by negative feedback?

Answer 28

No, adrenaline is not controlled by negative feedback.

Question 29

What are three effects of adrenaline on the body?

Answer 29

Increases heart and breathing rate Converts glycogen to glucose for energy in muscles Redirects blood to muscles (away from areas like the digestive system)

Question 30

What is the purpose of adrenaline’s effects?

Answer 30

To prepare the body for "fight or flight" — rapid physical action.

Question 31

What hormone lowers blood glucose levels?

Answer 31

Insulin.

Question 32

What hormone raises blood glucose levels?

Answer 32

Glucagon.

Question 33

Where are insulin and glucagon produced?

Answer 33

In the pancreas.

Question 34

What does insulin do when blood glucose levels are high?

Answer 34

Signals the liver and muscles to store glucose as glycogen Some excess glucose is stored as fat Blood glucose levels decrease

Question 35

What does glucagon do when blood glucose levels are too low?

Answer 35

Signals the liver to convert glycogen back into glucose Glucose is released into the bloodstream Blood glucose levels increase

Question 36

Is blood glucose regulation an example of negative or positive feedback?

Answer 36

Negative feedback.

Question 37

What happens in the liver when insulin is secreted?

Answer 37

The liver converts glucose into glycogen for storage.

Question 38

What happens in the liver when glucagon is secreted?

Answer 38

The liver converts glycogen back into glucose and releases it into the blood.

Question 39

What hormone causes the maturation of an egg in the ovary?

Answer 39

Follicle Stimulating Hormone (FSH).

Question 40

What hormone triggers ovulation (release of the egg)?

Answer 40

Luteinising Hormone (LH).

Question 41

What is the role of oestrogen in the menstrual cycle?

Answer 41

It repairs and thickens the uterus lining after menstruation.

Question 42

What is the role of progesterone in the menstrual cycle?

Answer 42

It maintains the uterus lining in preparation for a fertilised egg.

Question 43

When does oestrogen peak in the menstrual cycle?

Answer 43

Around day 12.

Question 44

When do FSH and LH peak in the menstrual cycle?

Answer 44

Around day 14, during ovulation.

Question 45

What happens to oestrogen levels after day 12?

Answer 45

They drop briefly during ovulation, then rise again with a second smaller peak around day 21.

Question 46

What happens to progesterone after ovulation?

Answer 46

It rises, peaks around day 21, then falls if fertilisation does not occur.

Question 47

What happens if the egg is not fertilised?

Answer 47

Progesterone levels fall, triggering menstruation and the cycle restarts.

Question 48

What is the approximate cost of one cycle of private IVF treatment?

Answer 48

£5000.

Question 49

Why does the NHS have to limit IVF funding?

Answer 49

Because it is expensive, and success rates decrease with age, so funding is prioritised.

Question 50

How does a woman’s age affect IVF success rates?

Answer 50

As age increases, IVF success rates decrease significantly.

Question 51

What was the IVF success rate for women under 35 in 2010?

Answer 51

32.2%.

Question 52

What was the IVF success rate for women aged 43-44 in 2010?

Answer 52

5%.

Question 53

Name two advantages of IVF.

Answer 53

Helps infertile couples have children. Embryos can be screened for genetic diseases.

Question 54

Name two disadvantages of IVF.

Answer 54

Low success rate, especially as age increases. Side effects from fertility drugs (e.g., headaches, OHS).

Question 55

What is Ovarian Hyperstimulation Syndrome (OHS)?

Answer 55

A condition where too many eggs develop, causing swelling and pain.

Question 56

Why is IVF emotionally and physically stressful?

Answer 56

Due to invasive procedures, hormone treatment, and uncertain outcomes.

Question 57

What are two ethical concerns about IVF?

Answer 57

Unused embryos may be destroyed, which some see as destroying life. Fear of creating "designer babies" with selected traits.

Question 58

What happens to excess amino acids in the body?

Answer 58

They are deaminated in the liver to form ammonia.

Question 59

Why must ammonia be converted in the body?

Answer 59

Because ammonia is toxic and cannot be allowed to accumulate.

Question 60

What is ammonia converted into in the liver?

Answer 60

Urea, which is less toxic and can be safely excreted.

Question 61

What is the process of removing the amino group from amino acids called?

Answer 61

Deamination.

Question 62

Which organs remove urea from the blood?

Answer 62

The kidneys.

Question 63

How is urea transported to the kidneys?

Answer 63

In the bloodstream.

Question 64

Which enzyme breaks down proteins into amino acids?

Answer 64

Protease.

Question 65

Where does digestion of proteins into amino acids occur?

Answer 65

In the stomach and small intestine.

Question 66

Why can’t the body store excess amino acids or proteins?

Answer 66

Because they can be toxic and the body lacks a safe storage mechanism for them.

Question 67

How is urea excreted from the body?

Answer 67

It is filtered by the kidneys and excreted in urine.

Question 68

What does ADH stand for?

Answer 68

Anti-diuretic hormone.

Question 69

Which part of the brain detects water levels in the blood?

Answer 69

The hypothalamus.

Question 70

Where is ADH released from?

Answer 70

The pituitary gland.

Question 71

What does ADH do to the kidney tubules?

Answer 71

It makes them more permeable to water.

Question 72

What happens when too little water is in the blood?

Answer 72

More ADH is released → more water is reabsorbed → concentrated urine.

Question 73

What happens when too much water is in the blood?

Answer 73

Less ADH is released → less water is reabsorbed → dilute urine.

Question 74

Is ADH regulation an example of negative or positive feedback?

Answer 74

Negative feedback.

Question 75

What happens to urine when ADH levels are high?

Answer 75

It becomes more concentrated and the volume decreases.

Question 76

What happens to urine when ADH levels are low?

Answer 76

It becomes more dilute and the volume increases.

Question 77

Why is ADH important for homeostasis?

Answer 77

It helps maintain a constant water balance in the blood plasma.

Question 78

What are gibberellins?

Answer 78

A group of plant hormones responsible for growth and development, especially germination.

Question 79

What is the main role of gibberellins in seeds?

Answer 79

To initiate seed germination.

Question 80

What effects do gibberellins have on plant growth?

Answer 80

They stimulate cell elongation and cause plants to grow taller.

Question 81

Name three uses of gibberellins in agriculture and horticulture.

Answer 81

End seed dormancy Promote flowering Increase fruit size

Question 82

What is seed dormancy, and how is it overcome?

Answer 82

It's a period when seeds do not germinate. Gibberellins can be used to break dormancy.

Question 83

What is ethene?

Answer 83

A hydrocarbon gas that speeds up fruit ripening and controls cell division in plants.

Question 84

What role does ethene play in the food industry?

Answer 84

It allows fruit to be picked unripe and then ripened during storage before being sold.

Question 85

How can the presence of ethene affect nearby fruit?

Answer 85

It causes nearby fruit to ripen faster, e.g. bananas speeding up the ripening of other fruits.

Question 86

Name two main functions of ethene in plants.

Answer 86

Speeds up ripening Controls cell division

Question 87

What are auxins?

Answer 87

A group of plant hormones that stimulate cell elongation and promote plant growth.

Question 88

Where are auxins mainly produced in a plant?

Answer 88

In the tips of stems and roots, known as the apical meristem.

Question 89

Name three uses of auxins in agriculture and horticulture.

Answer 89

Selective weedkillers Rooting powders Promoting growth in tissue culture

Question 90

How do selective weedkillers using auxins work?

Answer 90

They cause broad-leaved weeds to grow too quickly and die, without harming narrow-leaved plants like grass.

Question 91

Why are broad-leaved weeds affected more by selective weedkillers?

Answer 91

They absorb more hormone due to having larger leaves, which causes them to grow uncontrollably and die.

Question 92

What is a disadvantage of using selective weedkillers?

Answer 92

They can reduce biodiversity by killing plants that animals depend on for food.

Question 93

What is rooting powder and how does it work?

Answer 93

A powder containing synthetic auxins that helps stem cuttings develop roots quickly.

Question 94

What is tissue culture?

Answer 94

A technique used to grow new plants from small sections of a parent plant using hormones.

Question 95

What role do hormones play in tissue culture?

Answer 95

They stimulate cell division and elongation to help form new plants.