B5: Homeostasis And Response (triple)

Question 1

What is homeostasis?

Answer 1

Maintaining a stable internal environment.

Question 2

What is negative feedback?

Answer 2

It’s a body mechanism that allows the body to detect if something gets too high or too low and brings it back to normal.

Question 3

Describe how the nervous system reacts to a stimulus.

Answer 3

Stimulus
Receptor
Sensory neurone
Central nervous system 
Motor neurone
Effector 
Response

Question 4

What are synapses?

Answer 4

Connections between two neurones
Nerve signal is transferred by chemicals which diffuse across the gap
These chemical set off new electrical signals at the other end

Question 5

What is the purpose of a reflex?

Answer 5

To prevent injury

Question 6

Describe a reflex arc.

Answer 6

Stimulus 
Sensory neurone 
Relay neurone 
Motor neurone 
Effector

Question 7

What are endocrine glands?

Answer 7

Various glands that create and secrete hormones.

Question 8

Describe the function of the pituitary gland.

Answer 8

Produces many hormones, regulating many body conditions

Known as the master gland because it’s hormones effect other glands.

Question 9

Describe the function of the thyroid.

Answer 9

Produces thyroxine

This controls rate of metabolism, heart rate and temperature

Question 10

Describe the function of the ovaries.

Answer 10

Produce oestrogen

This is involved in the menstrual cycle

Question 11

Describe the function of the testes.

Answer 11

Produce testosterone

This controls puberty and sperm production

Question 12

Describe the function of the adrenal gland.

Answer 12

This produces adrenaline

This is used to prepare the body for a scary or stressful situation

Question 13

Describe the function of the pancreas.

Answer 13

Produces insulin

This is used to regulate blood glucose levels

Question 14

Describe the differences between nerves and hormones.

Answer 14

Nerves: fast action, act for a short time, act on a very precise area

Hormones: slower action, act for a long time, act in a more general way

Question 15

When is insulin added to the blood stream?

Answer 15

When blood sugar level is too high.

Question 16

When is glucagon added to the blood stream?

Answer 16

When blood sugar level is too low.

Question 17

Describe the four stages of the menstrual cycle.

Answer 17

1. The uterus lining breaks down in about 4 days.
2. The uterus lining build s up again. From day 4-14 it is a thick spongy layer full of blood vessels, ready to receive a fertilised egg.
3. An egg developers and is released from the ovary at day 14. This is called ovulation.
4. The wall is maintained for about 14 days until day 28. If no fertilised egg lands then the lining breaks down and the process starts over.

Question 18

What are the 4 hormones that control the menstrual cycle and what do they do?

Answer 18

Oestrogen: made in ovaries, causes uterus lining to grow, stimulates release of LH and inhibit release of FSH.
Progesterone: made in the ovaries in remains of the follicle after ovulation. Maintains the lining of the uterus. Inhibits release of LH and FSH
FSH (follicle stimulating hormone): made by the pituitary gland, causes egg to mature in structure called follicle. Stimulates the ovaries to produce oestrogen.
LH (luteinising hormone): made in the pituitary gland. Stimulates ovulation.

Question 19

What are the 5 main ways of contraception for females?

Answer 19

The pill (oestrogen and progesterone)
Contraceptive patch (oestrogen and progesterone)
Contraceptive implant (progesterone)
Contraceptive injection (progesterone)
Intrauterine device (T-shaped device inserted into the uterus to kill sperm and prevent implantation)

Question 20

What is the responsiblility of the cerebral cortex?

Answer 20

things like consciousness, intelligence, memory and language.

Question 21

What is the responsibility of the medulla?

Answer 21

unconscious activities like breathing and your heartbeat.

Question 22

What is the responsibility of the cerebellum?

Answer 22

muscle coordination.

Question 23

What is the sclera and it’s function?

Answer 23

the tough supporting wall of the eye that wraps around the majority of the surface area.

Question 24

What is the cornea and it’s function?

Answer 24

the transparent outer layer found over the front of the eye. it refracts light into the pupil.

Question 25

What is the iris and it's function?

Answer 25

it contains muscles that control the diameter of the pupil.

Question 26

What is the lens and it's function?

Answer 26

it focuses the light onto the retina.

Question 27

What is the retina and its function?

Answer 27

a group of receptor cells that are sensitive to light intensity and colour.

Question 28

What are the suspensory ligaments and ciliary muscle?

Answer 28

they control the shape of the lens.

Question 29

What is the optic nerve and its function?

Answer 29

it caries impulses from the receptor on the retina to the brain.

Question 30

Describe what happens to the eye in bright light.

Answer 30

circular muscles in the iris contract and the radial muscles relax. pupil gets smaller.

Question 31

Describe whats happens to the eye in dim light.

Answer 31

circular muscles in the iris relax and the radial muscles contract. pupil gets bigger.

Question 32

Describe whats happens to the eye when it is focusing on something close.

Answer 32

the ciliary muscle contracts and the senspensory muscle relaxes and becomes slackened. this makes the lens more curved so light can refract more.

Question 33

Describe whats happens to the eye when it is focusing on something far away.

Answer 33

the ciliary muscle relaxes and the senspensory muscle tightens. this makes the lens flatter so light refracts less.

Question 34

What type of lens is needed to correct someone who is long sighted (hyperopia)

Answer 34

convex (curves outwards)

Question 35

What type of lens is needed to correct someone who is short sighted? (myopia)

Answer 35

concave (curves inwards)

Question 36

What is the name of the process in the kidneys where substances are removed form the blood?

Answer 36

filtration

Question 37

What is the name of the process in the kidneys where specific substances are put back into the blood?

Answer 37

selective re-absorption.

Question 38

where does urea come form in the body?

Answer 38

when proteins are turned into fats and carbohydrates in the liver, ammonia is made as a byproduct. htis is converted into urea by the liver and removed from the blood stream by the kidneys.

Question 39

what happens to the ions in that blood stream at the kidneys?

Answer 39

they are removed and the amount (compared to water levels) is balanced and re-absorbed into the blood. the rest is removed form the body as urine.

Question 40

What hormone controls the concentration of urine?

Answer 40

anti-diuretic hormone (ADH)

Question 41

What hormone controls growth in plants?

Answer 41

Auxin

Question 42

What are names of the processes in which a plant grows in reaction to light and gravity?

Answer 42

phototropism | gravitropism/geotropism

Question 43

How does similar auxin distribution in plant roots and shoots cause one to grow up and the other down from a horizontal position?

Answer 43

in shoots, gravity causes auxin to accumulate beneath the tips promoting growth against gravity. in roots, the extra auxin at the bottom of the roots due to gravity inhibits growth, causing the roots to grow in the direction of gravity.

Question 44

Give commercial uses of auxins.

Answer 44

selective weed killers that disrupt the growth of weeds. growing from cuttings with rooting powder (these cant produce auxin without tips). growing cells in tissue culture.

Question 45

Give commercial uses of gibberellin.

Answer 45

to alter seed dormancy, changing when they germinate. to induce flowering. to grow larger fruits.

Question 46

Give commercial uses of ethene in agriculture.

Answer 46

controls cell division and stimulates enzymes. speed up ripening (on or off plant) delay ripening (chemicals that block ethene's effects).