B3

Question 1

Describe the role of sensory neurones

Answer 1

Sensory neurones deliver nervous (electrical) impulses to the CNS

Question 2

Give an example of an effector

Answer 2

Muscle, gland

Question 3

What is the purpose of a reflex action?

Answer 3

To stop you injuring yourself

Question 4

Describe the pathway of a reflex arc from stimulus to response

Answer 4

1) stimulus
2) receptor
3) sensory neurone
4) CNS
5) motor neurone
6) effector
7) response

Question 5

Describe the function of these structures in the eye: a) iris

    b) lens
    c) ciliary body

Answer 5

a) to control how much light renters the pupil
b) to refract lights, focusing it onto the retina
c) contains ciliary muscles, which are attached to suspending ligaments- they work together to alter the shape of the lens

Question 6

What term describes an eye condition in which a person can’t tell the difference between certain colours?

Answer 6

Colour blind

Question 7

What term describes someone who can’t focus on near objects?

Answer 7

Long-sighted

Question 8

Give the function of the cerebrum and the pituitary gland

Answer 8

• Cerebrum- responsible for consciousness, intelligence, memory and language
• Pituitary- gland that produces important hormones

Question 9

Describe two difficulties involved in investigating brain function

Answer 9

• Can be unethical if someone is severely brain damaged as they cannot give consent
• Relies on people who gave died donation their brains for research
• Can be problems when interpreting results of case studies

Question 10

What is the endocrine system?

Answer 10

Made up of the endocrine glands that produce hormones

Question 11

Give one role of thyroxine in the body

Answer 11

• Regulating metabolic rate
• growth
• protein synthesis

Question 12

Explain how negative feedback helps to control the level of thyroxine in the blood

Answer 12

•When the level of thyroxine in the blood is higher than normal, the secretion of TSH is inhibited.
Vice versa

Question 13

Describe the affect that adrenaline has on the body

Answer 13

• prepares you for ‘fight or flight’
• increases heart rate and blood pressure
• increases blood flow to muscles for increases respiration
• increases blood glucose level

Question 14

State where each of these hormones is produced and briefly describe its role in reproduction:

a) testerone
b) oestrogen
c) progesterone
d) FSH

Answer 14

a) produced in the testes. Stimulates sperm production. Main male sex hormone
b) produced in ovaries. Involved in menstrual cycle and promotes female sexual characteristics. Main female sex hormone
c) produced in ovaries. Helps to support pregnancy. Involved in menstrual cycle
d) released from pituitary gland in brain. Helps to control the menstrual cycle

Question 15

Explain how the combined pill prevents pregnancy when taken as a contraceptive

Answer 15

• involves progesterone and oestrogen
• prevents ovulation
• thins lining of uterus
• stimulates the production of thick cervical mucus

Question 16

Describe how one non-hormonal method of contraception works and list it’s pros and cons

Answer 16

• Condom worn over penis during intercourse to prevent spent entering vagina
• convenient
• cheap
• protects against STI’s
• 98% effective
• if it splits, becomes ineffective

Question 17

Explain how auxins make plant shoots bend towards the light

Answer 17

• plant shoots are positively phototrophic •move through plant in solution
• when shoot tip exposed to light, more auxins accumulate on the side in shade
• this make cells grow faster in shaded sided, so short bends towards light

Question 18

Describe the effects of ethane on plants

Answer 18

• produced by ageing leaves
• stimulates cells connecting leaf and plant to expand, breaking the cell walls and causing leaf to fall off plant
• also stimulates enzymes causing fruit to ripen

Question 19

Describe four ways in which plant hormones are used to control plant growth

Answer 19

• selective herbicides (weed killers)
• growing from cuttings with rooting powder
• producing seedless fruit using gibberellins and auxins
• controlling dormancy using gibberellin to make plants germinate at different times of year

Question 20

What is homeostasis? Why is it important?

Answer 20

• homeostasis is marinating a constant internal environment (blood glucose/sugar concentration, water content, body temp)
• important as it can be dangerous for your health if conditions vary too much from normal levels

Question 21

Explain how body temperature is reduced when you’re too hot

Answer 21

Hypothalamus;

1) erector muscles relax, so hairs lie flat
2) lots of sweat produced. When sweat evaporated, transfers energy in form of heat to environment, cooling you down
3) blood vessels close to skin dilate (widen). VASODILATION. Allows more blood to flow near surface so energy transferred to surrounding, cooling you down

Question 22

Describe the roles of insulin and glucagon in controlling a persons blood sugar level

Answer 22

• blood glucose (sugar) level too high- insulin added

* blood glucose level too low- glucagon added

Question 23

Explain how type 1 and type 2 diabetes can be treated

Answer 23

• type 1 - insulin injected after eating. Diet includes less carbohydrates
• type 2 - eating healthy diet, exercising regularly and losing weight if necessary. Drugs available to improve bodies reaction to insulin

Question 24

Describe how the water potential of tissue fluid may cause the cells to shrink

Answer 24

If there is a higher water potential inside the cell, there will be a net movement of water out of cell into tissue fluid. Causes cell to shrink

Question 25

Describe how the brain responds when it detects a fall in the water content of the blood

Answer 25

• pituitary gland releases more ADH
• ADH makes kidney reabsorb more water
• body then hydrated

Question 26

How does the kidney respond to an excess intake of water?

Answer 26

•kidney excretes more water meaning lots of dilute urine produced