Biology Paper 2: Homeostasis And Response

Question 1

Why do cells carry out respiration?

Answer 1

To release energy from glucose- uses enzymes

Question 2

What do enzymes need in order to work?

Answer 2

Very stable conditions- enzymes cannot work well if the conditions around them change to much

Question 3

What is homeostasis?

Answer 3

The regulation of internal conditions of a cell or organism to maintain optimum enzyme and cell function

Question 4

How is homeostasis used in the human body?

Answer 4

To keep the blood glucose concentration, the body temperature and water levels constant

Question 5

What does homeostasis consist of?

Answer 5

Automatic control systems making sure that the internal conditions of the body stay as constant as possible

Question 6

What can the automatic control systems in the human body involve?

Answer 6

The nervous system or endocrine system

Question 7

What do receptors do?

Answer 7

Detect changes in environment (the stimulus)

Question 8

What does the coordination centre do and what parts of the body does it involve?

Answer 8

.Receives and processes the information from receptor cells
.includes the brain, spinal cord and pancreas

Question 9

What do the effectors do and what parts of the body are involved?

Answer 9

.Carries out a response
.muscles or glands

Question 10

What does the nervous system consist of?

Answer 10

The CNS and other nerves running to and from the nervous system

Question 11

What does the CNS consist of?

Answer 11

The brain and spinal cord

Question 12

What is the key role of the nervous system?

Answer 12

Enables humans to react to their surroundings and coordinate behaviour, which is done from the reflex arc

Question 13

What happens when we touch a hot object?

Answer 13

.first the stimulus is detected by a receptor (in this case the receptor is the skin
.electrical impulses now pass along a sensory neurone to CNS
.at the end of the sensory neurone is a junction called a synapse, a chemical is released and this chemical diffuses across to a relay neurone in the CNS, where it triggers an electrical impulse
.The electrical impulse now passes along the relay neurone and reaches another synapse and a chemical is released again
.this chemical triggers an electrical impulse in a motor neurone
.the electrical impulse now passes down the motor neurone to an effector (in this case the effector is a muscle)
.the muscle now contracts and pulls the hand away from the heat
.pulling the hand away from the heat is the response

Question 14

What do reflexes do?

Answer 14

Because they are rapid, reflexes help protect us from danger

Question 15

What is the process for the reaction time required practical?

Answer 15

.person 1 sits on a still with good posture
.person 1 then places their forearm of their dominant arm across the table, with their hand overhanging the edge
.now person 2 holds a ruler vertically
.The 0cm mark should be between person 1s thumb and first finger
.person 2 then drops the ruler at a random time
.person 1 has to catch the ruler with their thumb and first finger as quickly as possible
.person 2 now records the measurement on the ruler that is level with the top of person 1s thumb
.test is repeated multiple times and a mean is calculated
.From these experiments, we can convert our results to a reaction time using a conversion table
.At the end the two people switch places to see the different reaction times

Question 16

What is the independent variable (changed) for reaction time require practical?

Answer 16

.person having their reaction time tested

Question 17

What is the dependent variable (measured) in three reaction time required practical?

Answer 17

Reaction time

Question 18

What are the three control variables (stay the same) in the reaction time required practical?

Answer 18

Starting distance between thumb and finger should be kept constant
.always measure the ruler at the top of the sun
.keep conditions on the room the same

Question 19

What happens if we allow any of our control variables to change?

Answer 19

It will affect our reaction time

Question 20

other variables that could affect reaction time:

Answer 20

.practice- the more someone does the experiment the better they could become at it
.trying the experiment with a different hand

Question 21

What is the body controlled by?

Answer 21

Chemicals called hormones- endocrine system

Question 22

What does the endocrine system consist of?

Answer 22

Glands that secrete hormones directly into the bloodstream

Question 23

How are hormones carried through the body

Answer 23

Through the bloodstream

Answer 24

.nervous system uses electrical impulses which travel neurones
.endocrine system uses hormones which are chemicals that are carried in the bloodstream
.signalling in the nervous system is very fast whereas the endocrine system has a slower more long lasting effect

Question 25

What does the pancreas do?

Answer 25

Releases hormones which are involved in controlling the concentration of glucose in the blood

Question 26

What do the ovaries and testes do?

Answer 26

Release hormones involved in puberty and reproduction

Question 27

What does the thyroid gland do?

Answer 27

Produces hormones which are involved in growth and regulating the body’s metabolic rate

Question 28

What do the adrenal glands do?

Answer 28

Release the hormone adrenaline which is produced in times of fear or stress

Question 29

What does the pituitary gland do?

Answer 29

Located in the brain, extremely important, scientists call it the master gland, released a number of different hormones into the blood depending on the conditions, acts on other glands and can trigger a range of different effects in the body

Question 30

Why is glucose needed by every cell?

Answer 30

To release energy by respiration- concentration of glucose must be kept constant- homeostasis

Question 31

What is blood glucose concentration monitored by?

Answer 31

The pancreas

Question 32

What happens when we eat something rich in carbohydrates?

Answer 32

Concentration of glucose can rise so the pancreas releases the hormone insulin

Question 33

How does insulin travel around the body?

Answer 33

Through the bloodstream- triggers body cells to take up glucose from the blood

Question 34

What does insulin trigger?

Answer 34

Liver and muscle cells to store excess glucose as a storage molecule called glycogen
Because glucose is now being taken out of the blood and stored, the concentration of glucose in the blood returns to a normal level