Intro & Temperature control

Question 1

State the definition of endotherm. (1)

Answer 1

An organism that controls their body temperature by homeostasis as well as altering their behaviour.

Question 2

State the definition of ectotherm. (1)

Answer 2

An organism that can’t control their body temperature internally – they control it by changing their behaviour.

Question 3

State the definition of negative feedback. (3)

Answer 3

• Receptors detect when level is too high or too low
• Information is communicated to effectors via nervous system or endocrine system
• Effectors respond to counteract the change – bringing the level back to normal

Question 4

State the definition of positive feedback. (2)

Answer 4

• Effectors respond to further increase the level away from the normal level
• This amplifies the change

Question 5

State the definition of homeostasis. (1)

Answer 5

Maintenance of a constant internal environment

Question 6

State three behavioural responses of ectotherms in temperature control. (3)

Answer 6

• Move towards/away from sun
• Increase breathing rate
• Alter body shape

Question 7

Describe how endotherms react to reduced body temperature. (4)

Answer 7

• Thermoreceptors in the skin detect change in external temperature
• Thermoreceptors in the hypothalamus detects change in internal temperature
• Hypothalamus sends impulse to effectors
• Effects include vasoconstriction, less sweating, hairs stand up to trap a layer of insulation, shivering and adrenaline and thyroxine is released to increase metabolism

Question 7

Describe how endotherms react to increased body temperature. (4)

Answer 7

• Thermoreceptors in the skin detect change in external temperature
• Thermoreceptors in the hypothalamus detects change in internal temperature
• Hypothalamus sends impulse to effectors
• Effects include vasodilation, more sweating, hairs lie flat, no shivering and no adrenaline and thyroxine is released

Question 7

State 3 advantages of being ectothermic that are disadvantages of being endothermic. (3)

Answer 7

• Ectotherms can use less energy from food for respiration
• Use more energy from food for growth
• Can survive long periods without food

Question 8

State 2 advantages of being endothermic that are disadvantages of being ectothermic. (3)

Answer 8

• Endotherms can remain active in low temperatures
• They can inhabit colder parts of the planet

Question 9

State the definition of a stimulus. (1)

Answer 9

Any change in the internal or external environment

Question 10

Describe how cell signalling produces a response. (3)

Answer 10

• Receptors need to communicate with effectors to produce a response
• Cell surface receptors allow cells to recognise the chemicals involved in cell signalling
• Cell signalling can occur between adjacent cells or distant cells

Question 11

Explain how a neuronal system is an example of cell signalling. (2)

Answer 11

• Cells communicate by secreting neurotransmitters
• They send signals to adjacent cells such as nerve or muscle cells

Question 12

Explain how a hormonal system is an example of cell signalling. (2)

Answer 12

• Cells release hormones which travel in the blood
• Act as signals to distant cells

Question 13

Exam question

Explain why many moths and bumblebees are described as endothermic.

Answer 13

They generate heat from respiration/ metabolism