Communication and Homeostasis, 5.1

Question 1

What conditions do living organisms need to maintain inside their cells? Why?

Answer 1

Suitable pH, suitable temperature, aqueous environment and freedom from toxins and excess inhibitors. As they affect enzyme acitivity.

Question 2

Examples of a changing external enviroment

Answer 2

Changes externally put a stress on the living organism such as the temperature changing

Question 3

Examples of a changing internal enviroment

Answer 3

Metabolic activities of cells, they use resources and produce waste which could be toxic, eg if CO2 is allowed to build up it will alter the pH

Question 4

Cell Signalling

Answer 4

The way in which cells communicate with each other

Question 5

What is the neuronal system?

Answer 5

Network of neurons, signal across synapse junctions, conduct signals quickly

Question 6

What is a hormonal system?

Answer 6

Use the blood to transport signals, endocrine organs secrete hormones, hormones are detected by target cells with specific receptors

Question 7

What makes a good communication system?

Answer 7

Covers whole body, enable communication between cells, communication is specific, rapid response, short and long term responses

Question 8

Homeostasis

Answer 8

Maintaining a constant internal environment despite changes in internal and external factors. Within narrow limits.

Question 9

Negative Feedback

Answer 9

Conditions in the body are brought back to the optimum, it reverses the change

Question 10

What occurs during negative feedback?

Answer 10

Receptor detects the change (stimulus) and sends an input to the coordination center, the coordination center sends an output to the effectors which respond

Question 11

Positive Feedback

Answer 11

Mechanism that increases the change taking the system further away from the optimum

Question 12

Why is positive feedback more dangerous?

Answer 12

It destabilizes the system and is harmful

Question 13

An example of positive feedback

Answer 13

During pregnancy, oxytocin is release to stretch the cervix more and more until to baby is born

Question 14

Stimulus

Answer 14

Change in environment causing a response

Question 15

Response

Answer 15

Change in behavior or physiology

Question 16

Ectotherm

Answer 16

Organism that relies on external sources of heat to maintain body temperature

Question 17

Ectotherm response to being too cold

Answer 17

Move into a sunny area, lie on a warm surface, expose a larger SA to the sun

Question 18

Ectotherm response to being too hot

Answer 18

Move out of the sun, move underground, reduced body surface exposed to the sun

Question 19

Ectotherm advantages

Answer 19

Less food used in respiration, more energy used in growth, need to find less food, won’t overheat as easily

Question 20

Ectotherm disadvantages

Answer 20

Less active in cool temperatures, at risk from predators in the cold

Question 21

Endotherm

Answer 21

Organism that uses heat from metabolic reactions to maintain body temperature as chemical reactions can be exergonic

Question 22

Endotherm response to being too cold

Answer 22

Sweat glands release less sweat, hairs stand up, vasoconstriction, increased respiration in the liver, skeletal muscles contract (shivering)

Question 23

Endotherm response to being too hot

Answer 23

Sweat glands secrete more sweat, hairs lie flat, increased panting, less respiration in the liver,
vasodilation

Question 24

Endotherm advantages

Answer 24

Maintain a constant body temperature, remain active at cold temperatures, inhabit colder parts of the planet

Question 25

Endotherm disadvantages

Answer 25

Most energy used to maintain body temperature, need more food, lower proportion of energy used for growth

Question 26

What happens if the temperature rises?

Answer 26

Molecules gain kinetic energy, move faster, are more likely to collide and more likely to collide with sufficient energy, rate of reaction increases, however, structure of proteins and enzymes can be affected

Question 27

Where are temperature receptors?

Answer 27

In the hypothalamus, detect core body temperature

Question 28

What is the sensory cell that detects changes in external temperatures?

Answer 28

Thermoreceptor