Co-ordination and Response

Question 1

2.80: What is the purpose of sensitivity in living organisms?

Answer 1

• All living organisms need to respond to changes in environment for survival
• Nervous system coordinated by the Brain allows body to respond to changes in environment
• Organisms additionally have reflexes for fast involuntary actions that protect body from damage

Question 2

2.80: What are the factors needed to respond to an environment?

Answer 2

• Stimuli
• Receptor
• Effector

Question 3

2.80: What are the stimuli?

Answer 3

Triggers a physical or behavioral change in the environment

Question 4

2.80: What is a receptor?

Answer 4

Specialised cells that detect changes in environment
E.g, Sensory Neurones in the finger detect heat

Question 5

2.80: What is an effector?

Answer 5

Part of body that carries out response to Stimuli
E.g Muscles in finger that contract to pull finger away from heat

Question 6

2.81: What is homeostasis?

Answer 6

Maintenance of a constant internal environment

Question 7

2.81: What is osmoregulation?

Answer 7

Maintenance of constant Water level in the body

Question 8

2.81: What is thermoregulation?

Answer 8

Maintenance of optimum body temperature for optimum enzyme activity

Question 9

2.93: What happens when you are too hot?

Answer 9

• When in hot environment, increase in body temperature is detected by Thermoreceptors
• As a result, series of changes occurs in body via thermoregulation
• Blood vessels near skin dilate via Vasodilation to increase blood flow to surface for heat loss
• Sweat glands excrete sweat to cool skin via evaporative cooling
• Hair Erector Muscles relax to lower Skin hair, trapping a thin insulating layer of air above - the Skin for heat loss

Question 10

2.93: What happens when you are too cold?

Answer 10

• When in Cold environment, decrease in body temperature is detected by Thermoreceptors
• As a result, series of changes occurs in body via thermoregulation
• Blood vessels near skin contract via Vasoconstriction to reduce blood flow to surface to minimise heat loss
• Sweat glands do not excrete sweat to prevent evaporative cooling
• Hair Erector Muscles contract to raise Skin hair, trapping a thick insulating layer of air above the skin to prevent heat loss

Question 11

2.94: What are the main hormones?

Answer 11

• Adrenaline
• Insulin
• Testosterone
• Progesterone
• Oestrogen

Question 12

2.94: What is the source of adrenaline?

Answer 12

Adrenal Gland

Question 13

2.94: What is the role of adrenaline?

Answer 13

Prepares body for ‘fight or flight’ response

Question 14

2.94: What is the effect of adrenaline?

Answer 14

Increases heart and breathing rate

Question 15

2.94: What is the source of insulin?

Answer 15

Pancreas

Question 16

2.94: What is the role of insulin?

Answer 16

Lowers blood Glucose levels

Question 17

2.94: What is the effect of insulin?

Answer 17

Initiates the conversion of blood Glucose into Glycogen to be stored in Liver and Skeletal muscle

Question 18

2.94: What is the source of testosterone?

Answer 18

Testes

Question 19

2.94: What is the role of testosterone?

Answer 19

Primary sex hormone in Males

Question 20

2.94: What is the effect of testosterone?

Answer 20

Increased levels initiate development of secondary sexual characteristics

Question 21

2.94: What is the source of progesterone?

Answer 21

Ovaries

Question 22

2.94: What is the role of progesterone?

Answer 22

Primary sex hormone in females to maintain pregnancy

Question 23

2.94: What is the effect of progesterone?

Answer 23

Maintains the Uterus lining to cushion fertilised Egg cell

Question 24

2.94: What is the source of oestrogen?

Answer 24

Ovaries

Question 25

2.94: What is the role of oestrogen?

Answer 25

Primary sex hormone in Females

Question 26

2.94: What is the effect of oestrogen?

Answer 26

Increased levels initiate development of secondary sexual characteristics including the menstrual cycle