14.4-5 Homeostasis and tropic responses

Question 1

Homeostasis

Answer 1

maintenance of a constant internal environment

Question 2

What does insulin do to the blood glucose level?

Answer 2

Insulin decreases blood glucose level

Question 3

Explain the concept of homeostatic control by negative feedback

Answer 3

The responses when conditions change from the ideal or set point and returns to this set point
- if the level of something rises, control systems reduce it again and vice versa

Question 4

Diabetes type 1

Answer 4

a disorder in which the pancreas fails to produce enough insulin

Question 5

How to treat type 1 diabetes

Answer 5

By injecting insulin. The extra insulin causes the liver to convert glucose into glycogen, reducing the blood glucose level

Question 6

Describe the control of blood glucose concentration (high blood glucose level)

Answer 6

1. pancreas secretes insulin into the blood
2. liver converts glucose into glycogen
3. blood glucose level decreases

Question 7

Describe the control of blood glucose concentration (low blood glucose level)

Answer 7

1. glucagon is secreted into blood
2. liver converts glycogne to glucose
3. blood glucose level increases

Question 8

Describe the maintenance of a constant internal body temperature (when too warm and insulation)

Answer 8

1. the hair erector muscle relaxes, lowering the hair
2. a thin insulating layer of air is trapped above the skin
3. more heat is lost to the environment

Question 9

Describe the maintenance of a constant internal body temperature (when too cold, insulation)

Answer 9

1. the hair erector muscle contracts, raising the hair
2. the hairs trap a thicker layer of air above the skin
3. the air insulates the skin against heat loss

Question 10

Role of brain in maintenance of a constant internal body temperature

Answer 10

The hypothalamus contains the body’s temperature monitoring centre.
- it recieves info from the heat and cold thermoreceptors in the skin and responds by sending impulses to effectors to return the body’s temp back to normal.

Question 11

Describe the maintenance of a constant internal body temperature (cold weather)

Answer 11

1. Decreased rate of sweating
2. vasocontriction
3. shivering
4. contraction of hair erector muscles
5. increase in metabollic rate

Question 12

Vasodilation

Answer 12

Arteriole gets wider = blood flow in skin capillaries increases = heat loss increases

Question 13

vasoconstriction

Answer 13

arteriole gets narrower = blood flow in skin capillaries decreases = heat loss decreases

Question 14

Gravitropism

Answer 14

response in whihc parts of a plant grow towards or away from gravity

Question 15

phototropism

Answer 15

response in which parts of a plant grow towards or away from the direction of the light source

Question 16

Role of auxin in controlling shoot growth

Answer 16

• made in the shoot tip
• diffuses through the plant from the shoot tip
• distributed unequally in reponse to light and gravity
• stimulates cell elongation

Question 17

Plant shoots growing towards the light HOW

Answer 17

1. tip of the shoots and roots produces auxin
2. tip of the shoot senses light
3. diffuses to shaded side of the shoot
4. auxin causes cell to elongate
5. the shaded side grows longer, causing the shoot to bend towards the light

Question 18

negative gravitropism

Answer 18

stem grows against the force of gravity

Question 19

positive geotropism

Answer 19

when a root grows in the direction of the force of gravity