CIE A Level Biology: Homeostasis Test
Questions and All Correct Answers.
Homeostasis - Answer Homeostasis is the regulation of the internal conditions of a cell or
organism to maintain optimum conditions for function, in response to internal and external
changes.
Why is homeostasis important - Answer Homeostasis is critically important for organisms as
it ensures the maintenance of optimal conditions for enzyme action and cell function
What sensory cells do - Answer Sensory cells can detect information about the conditions
inside and outside of the body
Physiological factors controlled by homeostasis in mammals - Answer Core body
temperature
Metabolic waste (eg. carbon dioxide and urea)
Blood pH
Concentration of glucose in the blood
Water potential of the blood
Concentration of the respiratory gases (carbon dioxide and oxygen) in the blood
What does homeostasis in mammals rely to transfer information between different parts of the
body - Answer Nervous system - information is transmitted as electrical impulses that travel
along neurones
Endocrine system - information is transmitted as chemical messengers called hormones that
travel in the blood
What do majority of homeostatis mechanisms use to maintain homeostatic balance - Answer
The majority of homeostatic control mechanisms in organisms use negative feedback to
maintain homeostatic balance (ie. to keep certain physiological factors, such as blood glucose
concentration, within certain limits)
What does a negative feedback control loop involve - Answer A receptor (or sensor) - to
detect a stimulus that is involved with a condition / physiological factor
A coordination system (nervous system and endocrine system) - to transfer information
between different parts of the body
An effector (muscles and glands) - to carry out a response
, Outcome of a negative feedback loop - Answer The factor / stimulus is continuously
monitored
If there is an increase in the factor, the body responds to make the factor decrease
If there is a decrease in the factor, the body responds to make the factor increase
3 Key homeostatic mechanisms - Answer Thermoregulation - the control of body
temperature
Osmoregulation - the control of the water potential of body fluids
The control of blood glucose concentration
These homeostatic mechanisms in mammals require information to be transferred between
different parts of the body. There are two coordination systems in mammals that do this:
The nervous system
The endocrine system
Outline the nervous system - Answer The human nervous system consists of:
The central nervous system (CNS) - the brain and the spinal cord
The peripheral nervous system (PNS) - all of the nerves in the body
It allows us to make sense of our surroundings and respond to them and to coordinate and
regulate body functions. Information is sent through the nervous system as nerve impulses -
electrical signals that pass along nerve cells known as neurones. A bundle of neurones is known
as a nerve.. Neurones coordinate the activities of sensory receptors (eg. those in the eye),
decision-making centres in the central nervous system, and effectors such as muscles and
glands
Outline the endocrine system - Answer A hormone is a chemical substance produced by an
endocrine gland and carried by the blood. They are chemicals which transmit information from
one part of the organism to another and bring about a change. They alter the activity of one or
more specific target organs
Hormones are used to control functions that do not need instant responses. The endocrine
glands that produce hormones in animals are known collectively as the endocrine system. A
gland is a group of cells that produces and releases one or more substances (a process known as
secretion)
Why do endocrine glands have good supply - Answer Endocrine glands have a good blood
supply as when they make hormones they need to get them into the bloodstream (specifically
the blood plasma) as soon as possible so they can travel around the body to the target organs to
bring about a response
Questions and All Correct Answers.
Homeostasis - Answer Homeostasis is the regulation of the internal conditions of a cell or
organism to maintain optimum conditions for function, in response to internal and external
changes.
Why is homeostasis important - Answer Homeostasis is critically important for organisms as
it ensures the maintenance of optimal conditions for enzyme action and cell function
What sensory cells do - Answer Sensory cells can detect information about the conditions
inside and outside of the body
Physiological factors controlled by homeostasis in mammals - Answer Core body
temperature
Metabolic waste (eg. carbon dioxide and urea)
Blood pH
Concentration of glucose in the blood
Water potential of the blood
Concentration of the respiratory gases (carbon dioxide and oxygen) in the blood
What does homeostasis in mammals rely to transfer information between different parts of the
body - Answer Nervous system - information is transmitted as electrical impulses that travel
along neurones
Endocrine system - information is transmitted as chemical messengers called hormones that
travel in the blood
What do majority of homeostatis mechanisms use to maintain homeostatic balance - Answer
The majority of homeostatic control mechanisms in organisms use negative feedback to
maintain homeostatic balance (ie. to keep certain physiological factors, such as blood glucose
concentration, within certain limits)
What does a negative feedback control loop involve - Answer A receptor (or sensor) - to
detect a stimulus that is involved with a condition / physiological factor
A coordination system (nervous system and endocrine system) - to transfer information
between different parts of the body
An effector (muscles and glands) - to carry out a response
, Outcome of a negative feedback loop - Answer The factor / stimulus is continuously
monitored
If there is an increase in the factor, the body responds to make the factor decrease
If there is a decrease in the factor, the body responds to make the factor increase
3 Key homeostatic mechanisms - Answer Thermoregulation - the control of body
temperature
Osmoregulation - the control of the water potential of body fluids
The control of blood glucose concentration
These homeostatic mechanisms in mammals require information to be transferred between
different parts of the body. There are two coordination systems in mammals that do this:
The nervous system
The endocrine system
Outline the nervous system - Answer The human nervous system consists of:
The central nervous system (CNS) - the brain and the spinal cord
The peripheral nervous system (PNS) - all of the nerves in the body
It allows us to make sense of our surroundings and respond to them and to coordinate and
regulate body functions. Information is sent through the nervous system as nerve impulses -
electrical signals that pass along nerve cells known as neurones. A bundle of neurones is known
as a nerve.. Neurones coordinate the activities of sensory receptors (eg. those in the eye),
decision-making centres in the central nervous system, and effectors such as muscles and
glands
Outline the endocrine system - Answer A hormone is a chemical substance produced by an
endocrine gland and carried by the blood. They are chemicals which transmit information from
one part of the organism to another and bring about a change. They alter the activity of one or
more specific target organs
Hormones are used to control functions that do not need instant responses. The endocrine
glands that produce hormones in animals are known collectively as the endocrine system. A
gland is a group of cells that produces and releases one or more substances (a process known as
secretion)
Why do endocrine glands have good supply - Answer Endocrine glands have a good blood
supply as when they make hormones they need to get them into the bloodstream (specifically
the blood plasma) as soon as possible so they can travel around the body to the target organs to
bring about a response
