Section 38.3 (Exam 3)

Question 1

What is the range of temperatures in which most cells can survive?

Answer 1

a narrow range of 0-45 Celsius

Question 2

What happens to cells below 0 Celsius?

Answer 2

Ice crystals form and damage cell structures

Question 3

How do some cells survive below 0 Celsius?

Answer 3

Some animals have antifreeze molecules in their blood that help them resist freezing; others can survive freezing

Question 4

What is one example of a frog that survives below freezing temperatures?

Answer 4

Rana sylvatica

Urea and glucose accumulation act as cryoprotectants

Intracellular water redistributed to ECF

Question 5

Why is redistributing intracellular water to the ECF effective for countering freezing?

Answer 5

If intracellular water freezes it can puncture cell structures. By relocating it, it avoids damage to cell structures.

Question 6

Why do cells die above 45 Celsius?

Answer 6

Proteins begin to denature and lose function

Question 7

What are example of organisms that can survive above 45 Celsius?

Answer 7

Specialized algae that grows in hot springs at 75 Celsius

Some archaea live at near 100 Celsius

Question 8

What are heat shock proteins (HSPs)?

Answer 8

Chaperone proteins that stabilize other proteins and prevent denaturation

Question 9

What range do most cells survive in, and what do they have that allows them to do so?

Answer 9

0-45 Celsius

Thermoregulatory adaptations

Question 10

Biochemical reactions are temperature-sensitive. How does this affect their rate of reaction?

Answer 10

The rate of reaction increases as temperature increases

Question 11

What is the Q_10?

Answer 11

A way of describing temperature sensitivity of a reaction.

Rate of reaction at one temperature divided by rate of the same reaction at a temperature 10 degrees Celsius lower.

Question 12

If a reaction is not temperature sensitive, what is its Q_10?

Answer 12

1, because the rate of reaction 10 degrees lower or higher would be the same rate.

Question 13

What does it mean if Q_10 is 2?

Answer 13

As the temperature increases by 10 degrees Celsius, the rate of the reaction doubles.

Question 14

What range of Q_10 do most biological reactions have?

Answer 14

2-3

Question 15

Why does change in body temperature disrupt physiology?

Answer 15

Not all biochemical reactions have the same Q_10.

Question 16

Why can shifting the reaction rate for one reaction disrupt the entire biological network?

Answer 16

Products of one reaction are reactants for other reactions.

All the reactions are linked in complex networks.

If one product is produced incorrectly, all sequential reactions will not occur correctly.

Question 17

Some animals couple their body temperature to the environmental temperature, such as fish. How do fish remain active in differing temperatures?

Answer 17

In the cold, fish can acclimatize, and have a higher metabolic rate

Question 18

What is one mechanism for acclimatization?

Answer 18

Expressing isozymes

Question 19

What are isozymes?

Answer 19

Different forms of an enzyme that have different temperature optima

Question 20

What must the body do in response to hyperthermia (overheating)?

Answer 20

reduce heat-generating muscular work and increase heat loss

Question 21

How does the body reduce heat-generating muscular work and increase heat loss to cope with hyperthermia (overheating)?

Answer 21

heat induced cramps cause athletes to stop exercising

deprive muscle of energy

Question 22

How does the body deprive a muscle of energy when it needs to cool down?

Answer 22

Pyruvate kinase deactivates at 40 degrees Celsius, shutting down ATP production and muscle function