# AP Biology : Understand organisms' energy use

## Example Questions

### Example Question #1 : Understand Organisms' Energy Use

A lizard warms himself up on a rock that has been out in the sun. When the sun sets, his body temperature drops back down. Is the lizard endothermic or exothermic?

Endothermic; the lizard regulates his own body temperature

Exothermic; the lizard's body temperature is governed by external, environmental factors

Endothermic; the lizard's body temperature is governed by external, environmental factors

Exothermic; the lizard can regulate his own body temperature with help from external environmental factors

Exothermic; the lizard regulates his own body temperature

Exothermic; the lizard's body temperature is governed by external, environmental factors

Explanation:

Endothermic organisms can regulate their own body temperature via internal regulation mechanisms independent of environmental factors. For example, a dog is able to cool itself down in the heat of day by panting. Exothermic organisms cannot internally regulate their own body temperature. Rather, they have external regulation, and they depend on environmental factors. The lizard mentioned cannot regulate his own body temperature. In order to warm up, he must find sunlight and heat to increase his body temperature; in order to cool down he may find shade or seek refuge underground. Exothermic organisms are extremely dependent on climate to carry out life functions.

### Example Question #1 : Understand Organisms' Energy Use

Which of the following best explains the principle of allocation with regards to energy?

Organisms can access stored energy for life functions even after they have expended significant energy when chasing prey

Energy is saved for internal or external regulation of the organism

If large amounts of energy are spent catching prey, organisms must spend time recovering the lost energy

When an organism expends energy catching prey, it does not have energy for other functions

Energy is equally distributed between daily life functions

When an organism expends energy catching prey, it does not have energy for other functions

Explanation:

The principle of allocation, in regards to energy, states that energy spent doing one activity takes away the energy that could be spent doing other activities. For example, if an organism expends energy chasing prey, the organism will be tired and will have less energy to carry out other functions.

### Example Question #2393 : Ap Biology

Which law of thermodynamics states that there will always be an increase in entropy due to some energy not being able to be utilized in a reaction and lost from the system?

Fourth law

Second law

Third law

First law

Zeroth law

Second law

Explanation:

The Second Law of Thermodynamics states that during an reaction that some energy will not be completely transferred and will ultimately be lost as heat to increase the entropy of the universe.

### Example Question #1 : Understand Organisms' Energy Use

Which is not true of endothermic organisms?

They have a greater energy requirement than exotherms

Humans are an example of an endothermic organism

They have a lower energy requirement than exotherms

Their body temperature remains within a narrow range

They have a lower energy requirement than exotherms

Explanation:

Endotherms regulate their body temperature, keeping it within a narrow range. To do this, they require a large amount of energy (food), more than exotherms which do not regulate their own body temperature and thus have a lower energy requirement.

### Example Question #5 : Understand Organisms' Energy Use

Which is true of ectotherms?

Humans are an example of exotherms

They have a greater energy requirement than endotherms

Their body temperature fluctuates considerably

Their body temperature remains within a narrow range

Their body temperature fluctuates considerably

Explanation:

Ectotherms do not regulate their body temperature; their body temperature fluctuates due to their external environment.

### Example Question #2391 : Ap Biology

Which is not a method that endotherms may use to regulate their body temperature in a cold environment?

Vasoconstriction

Shivering thermogenesis

Thermoregulation

Vasodilation

Vasodilation

Explanation:

Vasodilation allows more heat to escape via the blood vessels. Thus, in a cold environment, this would be counterproductive. Vasoconstriction shrinks the blood vessels so that less heat escape. Shivering thermogenesis produces heat by converting ATP to kinetic energy. Thermoregulation is the term describing organisms maintaining their internal body temperature.

### Example Question #1 : Understand Organisms' Energy Use

In the following scenarios, which organism is likely an ectotherm?

A dog panting when exposed to hot weather

A human shivering when exposed to cold weather

A bear hibernating during winter

A snake laying on a dark rock during a cool day

A snake laying on a dark rock during a cool day

Explanation:

An ectotherm relies on external sources to regulate its body temperature. The snake lies on the dark rock to absorb heat energy from the sun, to warm its body during the cool day. Animals that hibernate, such as bears, cannot be ectotherms. Hibernating animals downregulate their body’s metabolism and thus body temperature; ectotherms cannot control their body temperature. Humans are endotherms, and like other endotherms, shiver when cold to increase their body temperature through expending energy (“shivering thermogenesis”). Dogs are endotherms, and pant when hot to cool their body temperature by expelling heat.

### Example Question #2401 : Ap Biology

Which is true of endotherms?

They generate heat internally to maintain their body temperature

They rely on photosynthesis to generate energy

Shivering thermogenesis can be used to maintain homeostasis in cold weather

Sweating can be used to maintain homeostasis in cold weather

Shivering thermogenesis can be used to maintain homeostasis in cold weather

Explanation:

Endotherms maintain a relatively constant body temperature, independent of their external environment. They can shiver when cold to increase their body temperature through expending energy (“shivering thermogenesis”).

### Example Question #9 : Understand Organisms' Energy Use

Compared to ectotherms, endotherms have a

Lower metabolic rate

Greater fluctuation in body temperature

Shorter lifespan

Higher metabolic rate