Biology Ka4

Question 1

What is homeostasis?

Answer 1

The maintenance of a constant internal body environment

Question 2

What do enzymes control?

Answer 2

All the functions of a cell (metabolism)

Question 3

What internal conditions are controlled by enzymes?

Answer 3

Water content of the body.
Blood glucose concentration.
Body temperature.

Question 4

What is water concentration controlled by?

Answer 4

Osmosis

Question 5

The concentration of water in your blood should be the same as what?

Answer 5

The salt concentration in your cells

Question 6

What controls the amount of water in your body?

Answer 6

The kidneys by producing urine or sweat

Question 7

What controls the concentration of urine?

Answer 7

Nerves and hormones.

Question 8

The body controls the level of blood with what?

Answer 8

Hormones secreted by the pancreas.

Question 9

What lowers blood glucose?

Answer 9

Insulin

Question 10

What raises blood glucose?

Answer 10

Glycogen

Question 11

Mammals and birds keep a __?

Answer 11

Constant body temperature

Question 12

What does the body do to warm up?

Answer 12

Shivers, hairs stand on end, sweating stops

Question 13

What does the body do to cool down?

Answer 13

Sweats, hairs lie flat, blood supply to skin drops

Question 14

What systems work together to maintain a constant body temperature?

Answer 14

Nervous and hormone systems

Question 15

What is the endocrine system?

Answer 15

Slower but acts for longer. Carried in blood to all organs, affects target organ only

Question 16

What do the receptors do?

Answer 16

Detects a stimulus (either the level of something is too high or too low )

Question 17

What does the coordination centre do?

Answer 17

Receives and processes the information, then organises a response

Question 18

What does the effector do?

Answer 18

Produces a response which counteracts the change and restores the optimum level

Question 19

What are the stages of the control system?

Answer 19

Stimulus, receptor, coordination centre, effector

Question 20

What are the types of receptors?

Answer 20

Light (eyes)
Sound (ears) 
Change in position (ears)
Taste (tongue)
Smell (nose)
Touch, pressure, pain, temp (skin)

Question 21

How does water leave the body?

Answer 21

Through the lungs, skin, kidneys (urine)

Question 22

How do excess ions leave the body?

Answer 22

Kidneys (urine)

Question 23

What are the internal conditions of the body which must be controlled?

Answer 23

Water content, ion content and temperature

Question 24

Why is it important to keep the body temperature constant?

Answer 24

To keep the body at a temperature at which enzymes work best

Question 25

Explain what happens when a sensory receptor detects a stimulus

Answer 25

The info is sent as an electrical impulse along special cells called neurons. They stretch to make the connections. The impulse travels along the neurone until it reaches the central nervous system. The cells that do this are the sensory neurones.

Question 26

What are nerves?

Answer 26

A bundle of hundreds of thousands of neurons

Question 27

What are the three neurons?

Answer 27

Relay neurones Sensory neurones Motor neurones

Question 28

What are neurones covered with?

Answer 28

A fatty layer called myelin sheath that acts as an insulator and speeds up the transmission of the impulse but is not continuous

Question 29

What are the cells called that travel along the neuron until it reaches the central nervous system?

Answer 29

The sensory neurones

Question 30

What does the nervous system let u do?

Answer 30

Take in information from your surroundings and respond in the right way

Question 31

What are reflexes?

Answer 31

Automatic responses

Question 32

Why are reflexes important?

Answer 32

Because they take care of basic body functions and protect you from harm

Question 33

What are reflex actions?

Answer 33

Automatic and rapid responses to stimuli

Question 34

What are some examples of reflex actions?

Answer 34

Breathing and moving the food through your gut

Question 35

It takes the nervous impulse less time to travel a distance along a neurone then is does for the arm to start moving. Explain why

Answer 35

The diffusion of the chemicals are much slower and the impulse has to cross two synapses

Question 36

What are the steps of the nervous system ?

Answer 36

Stimulus ➡️ receptor ➡️ sensory neurone ➡️ coordinator (CNS) ➡️ motor neurone ➡️ effector ➡️ response

Question 37

Explain how the nervous system works

Answer 37

The receptor sends an impulse along a sensory neurone as a result of a change in the environment (stimulus). The coordinator (CNS) processes the info. It sends impulses down motor neurones. The impulses from the motor neurones stimulate the effectors to create a response.

Question 38

Explain how synapses work

Answer 38

Neurones do not directly touch each other, there are junctions between them called synapses which form gaps. A chemical called a neurotransmitter releases and diffuses across the gap. When the chemical hits the receptors on the other side, the electrical impulse continues. Synapses mean impulses can only travel one way along the neurones

Question 39

Where are relay neurones found?

Answer 39

In the spinal cord

Question 40

Explain the reflex actions when pricking your finger on a pin

Answer 40

``` Stimulus = drawing pin Receptor = pain Coordinator = sensory, relay, motor neurones Effector = muscles to hand Response = withdrawing hand ```

Question 41

Label the reflex arc (on paper)

Answer 41

.

Question 42

A bee is flying towards a mans eye. What is the reflex in steps

Answer 42

Light receptor in eye ➡️ sensory neurone ➡️ relay neurone ➡️ motor neurone ➡️ eyelid muscle ➡️ blinking

Question 43

Explain what happens when a receptor detects a stimulus

Answer 43

The receptor detects a change in the environment. The information is sent to the CNS where the information is processed and a response is created as an electrical impulse down a sensory neurone to a gap called a synapse to the relay neurone. It passes through to the other end of the relay neurone, along the other gap to the motor neurone. It is then sent to the effector the response is produced