B3

Question 1

Homeostasis

Answer 1

regulation (balance) of the internal conditions of a cell or organism to maintain optimum conditions for enzyme function and all cell functions in response to internal and external changes.

Question 2

what does homeostasis control

Answer 2

blood glucose concentration
body temperature
water levels.

Question 3

Receptor cells

Answer 3

these are specialised cells that detect a stimulus (changes in the environment).

Question 4

The human nervous system order

Answer 4

stimulus 🡪 receptor 🡪 coordinator 🡪 effector 🡪 response

Question 5

Sensory neurone

Answer 5

these carry impulses from the receptors to the central nervous system (CNS).

Question 6

Relay neurones

Answer 6

these connect the sensory neurones to the motor neurones in the CNS.

Question 7

Motor neurones

Answer 7

these carry impulses from the CNS to an effector.

Question 8

brain

Answer 8

e brain controls complex behaviour. It is made of billions of interconnected neurones and has different regions that carry out different functions.

Question 9

three main structure in the brain

Answer 9

cerebral cortex – is the outer ‘wrinkled’ layer of the brain. It is responsible for intelligence, language, memory and consciousness.
cerebellum – is located at the lower part of the back of the brain and is responsible for voluntary coordination of the muscles.
medulla – is located in the lower part of the brain stem. It is responsible for involuntary coordination such as breathing, swallowing and heart rate.

Question 10

cornea

Answer 10

Transparent layer at the front of the eye; it refracts light into the eye.

Question 11

iris

Answer 11

The coloured part of the eye; contains muscles that control the amount of light entering the eye.

Question 12

pupil

Answer 12

The hole in the middle of the iris that lets light in. Its diameter is controlled by the iris.

Question 13

lens

Answer 13

A transparent, biconvex structure in the eye that refracts light onto the retina.

Question 14

retina

Answer 14

Thin layer of tissue at the back of the eye that contains receptor cells for light and colour.

Question 15

sclera

Answer 15

Tough white supporting wall of the eye.

Question 16

ciliary muscles

Answer 16

Muscles that are connected to the lens by the suspensory ligaments; they change the shape of the lens.

Question 17

suspensory ligaments

Answer 17

These connect the lens to the ciliary muscles.

Question 18

optic nerve

Answer 18

Carries impulses from the retina to the brain.

Question 19

What is hyperopia? How can it be corrected?

Answer 19

Long-sightedness, it can be corrected with convex lenses

Question 20

What is myopia? How can it be corrected?

Answer 20

Short-sightedness, it can be corrected with concave lenses

Question 21

endocrine system

Answer 21

The endocrine system is composed of glands which secrete chemicals called hormones directly into the bloodstream.

Question 22

pituitary gland

Answer 22

The pituitary gland in the brain is often called a ‘master gland’ as it produces and secretes many hormones into the blood.
The hormones are released in response to changes in body conditions.

Question 23

thyroid

Answer 23

The thyroid produces and secretes the hormone thyroxine. Thyroxine regulates the metabolic rate, this is the rate at which energy is released in the body. Thyroxine also regulates breathing, heart rate and body temperature.

Question 24

Negative feedback:

Answer 24

occurs when there is a change in the body (i.e. blood glucose increases)
the nervous system detects the change
this stimulates an opposite hormonal response
this reverses the effect back to homeostasis.

Question 25

Positive Feedback: (less common)

Answer 25

a change starts the nervous system detects the change then stimulates more hormones to be released to accelerate the change.

Question 26

ovaries

Answer 26

he ovaries produce and secrete the hormones oestrogen and progesterone. Oestrogen controls the development of secondary sexual characteristics in females and inhibits FSH and stimulates the pituitary gland to produce LH. Progesterone maintains the lining of the uterus during the menstrual cycle.

Question 27

testes

Answer 27

The testes produce and secrete the hormone testosterone. It controls the development of secondary sexual characteristics in males.

Question 28

FSH

Answer 28

pituitary glands Stimulates egg ripening and oestrogen production (in ovaries

Question 29

Oestrogen

Answer 29

Ovaries Lining of the womb to develop. Stimulates pituitary gland to make LH

Question 30

LH

Answer 30

Pituitary Gland Stimulates egg release and progesterone production in the ovaries

Question 31

Progesterone

Answer 31

Ovaries Maintains the lining of the womb

Question 32

Vasoconstriction

Answer 32

If the body temperature is too low, blood vessels constrict (vasoconstriction), sweating stops and skeletal muscles contract (shiver).

Question 33

Vasodilation

Answer 33

If the body temperature is too high, blood vessels dilate (vasodilation) and sweat is produced from the sweat glands. Both these mechanisms cause a transfer of energy from the skin to the environment.

Question 34

Blood glucose concentration

Answer 34

Blood glucose concentration TOO HIGH The PANCREAS releases insulin GLUCOSE is moved from the blood into the cells LIVER and MUSCLE cells convert excess GLUCOSE into GLYCOGEN for storage

Question 35

Type 1 diabetes

Answer 35

A disorder in which the pancreas fails to produce enough insulin. The lack of insulin causes uncontrolled high blood glucose levels. Type 1 is normally treated with insulin injections.

Question 36

Type 2 diabetes

Answer 36

A disorder where the body cells no longer respond to insulin produced by the pancreas. Obesity is a risk factor for type 2 diabetes. Type 2 is normally treated by controlling the carbohydrate in the diet and by exercise.

Question 37

Hypertonic

Answer 37

more concentrated solution than in the cells

Question 38

Isotonic

Answer 38

same concentration as the solution in the cell

Question 39

Hypotonic

Answer 39

more dilute than the solution in the cells

Question 40

high diet in protein

Answer 40

Diet high in proteins Digestive system proteins 🡪 amino acids Liver amino acids 🡪 ammonia (deaminated) ammonia 🡪 urea Kidneys Urea is filtered from the blood and excreted from the body in urine

Question 41

What does deaminated mean?

Answer 41

An amino group is removed from an amino acid.