Biology - Response and regulation

Question 1

What are neurons?

Answer 1

Neurons are long cells which carry electrical signals along their length.

Question 2

What is a synapse?

Answer 2

A tiny gap at the junction between two nerve cells, which nerve signals must cross.

Question 3

What are receptors, coordinators and effectors?

Answer 3

-Receptors - sense organs (eyes, ears, nose, etc)
-Coordinator - Spinal cord, brain
-Effector - muscles, glands

Question 4

How does information flow from the receptors to the effectors in the nervous system?

Answer 4

1)stimulus
2)Receptor
3)Sensory neuron
4)Relay neuron
5)Motor neuron
6)Effector
7)response

Question 5

What is a stimulus?

Answer 5

Something that sets off a reaction in the nervous system, for example, light, heat, etc.

Question 6

What are the stimuli which cause receptors/sense organs to impulse?

Answer 6

Skin - Temperature, pressure and pain
Tongue - Chemical tastes (in food and drink)
Nose - Chemical smells (in the air)
Eye - Light
Ear - Sound

Question 7

What are examples of an effector responding to stimuli?

Answer 7

-a muscle contracting to move an arm
-a muscle contracting to alter pupil diameter in the eye
-a gland releasing a hormone into the blood

Question 8

What are three words to describe a reflex action?

Answer 8

A reflex action is a protective, automatic and rapid response to a stimulus.

Question 9

What is the difference between a normal reaction and a reflex action?

Answer 9

A reflex reaction does not include the brain. Instead the spinal cord coordinates the response so the impulse can reach the effector quicker.

Question 10

What is a sensory neuron?

Answer 10

The nerve cell that transmits electrical impulses from receptors in the sense organs to the CNS.

Question 11

What is a relay neuron?

Answer 11

The nerve cell that transmits electrical impulses from sensory neurones to motor neurones.

Question 12

What is a motor neuron?

Answer 12

The nerve cell that carries electrical impulses from the CNS to effectors such as muscles or glands.

Question 13

What is the order of the impulse pathway?

Answer 13

1.A receptor cell passes an electrical impulse along the sensory neurone.
2.The sensory neurone reaches the coordinator, the CNS.
3.The sensory neurone connects to a relay neurone, via a synapse, inside the CNS.
4.The relay neurone connects to a motor neurone, via a synapse, inside the CNS.
5.The motor neurone leaves the CNS and the impulse is carried to the effector.

Question 14

What is the function of the cornea?

Answer 14

Clear area of the sclera, it refracts light - bends it as it enters the eye.

Question 15

What is the function of the iris?

Answer 15

Muscles which alter the size of the pupil, controlling the amount of light entering the eye.

Question 16

What is the function of the lens?

Answer 16

Focuses light onto the retina.

Question 17

What is the function of the retina?

Answer 17

Contains the light receptor cells.

Question 18

What is the function of the optic nerve?

Answer 18

Carries impulses between the retina and the brain.

Question 19

What is the function of the sclera?

Answer 19

White, tough outer layer.

Question 20

What is the function of the choroid?

Answer 20

Pigmented middle layer with many blood vessels. It absorbs light to avoid reflection and nourishes the retina.

Question 21

What is the function of the blind spot?

Answer 21

Where the optic nerve leaves the retina

Question 22

What is the function of the pupil?

Answer 22

Hole in the centre of the iris allows for light to get through

Question 23

What is homeostasis?

Answer 23

Homeostasis is the maintenance of a constant internal environment to keep conditions at an optimum.

Question 24

What are hormones?

Answer 24

Chemical messenger produced in glands and carried by the blood to specific organs in the body.

Question 25

What is insulin?

Answer 25

A hormone that regulates the level of sugar in the blood and can be produced by genetically modified bacteria.
Produced by pancreas

Question 26

What is negative feedback system?

Answer 26

if the level of something rises, control systems reduce it again
if the level of something falls, control systems raise it again

Question 27

How is blood glucose controlled by negative feedback? High and low concentration

Answer 27

After a meal
-Glucose absorbed
-Pancreas detects increase in glucose
-Pancreas releases insulin which travels to liver
-Liver converts glucose into glycogen for storage.

Following exercise
-Glucose is used up in respiration
-Pancreas detects decrease in glucose
-Pancreas releases glucagon which travels to liver
-Pancreas converts stored glycogen back into glucose.

Question 28

What do hairs on the skin do when warm and why?

Answer 28

-The hair erector muscle relaxes, lowering the hair
-A thin insulating layer of air is trapped above the skin
-More heat is lost to the environment

Question 29

What do hairs on the skin do when cold and why?

Answer 29

-the hair erector muscle contracts, raising the hair
-the hairs trap a thicker layer of air above the skin
-the air insulates the skin against heat loss

Question 30

What is vasoconstriction?

Answer 30

Vasoconstriction is a response to being too cold. The process involves the narrowing of blood vessels at the skin surface to reduce heat loss through the surface of the skin.

Question 31

What is vasodilation?

Answer 31

Vasodilation is a response to being too hot. The process includes the widening of blood vessels at the skin surface to increase heat loss through the surface of the skin.

Question 32

What are tropisms?

Answer 32

Plant growth response to light, gravity or water.

Question 33

What are responses to stimuli of different parts of the plant?(tropisms)

Answer 33

Stem response to light is positive phototropism (grows towards the light).

Root response to gravity is positive geotropism (grows in the direction of the force of gravity).

Question 34

What is auxin?

Answer 34

Auxin is a family of plant hormones. Auxin change the rate of elongation in plant cells, controlling their length.

Question 35

How does light affect auxin in a plant?

Answer 35

In a stem, the shaded side contains more auxin and grows longer – causing the stem to bend towards the light.

Question 36

What is gravitropism?

Answer 36

Gravitropism is a growth response in a plant to the force of gravity.

Question 37

What is phototropism?

Answer 37

Phototropism is a growth response in a plant due to light.

Question 38

What is type 1 diabetes?

Answer 38

Type 1 diabetes is caused by damage to the beta cells in the pancreas which produce insulin. The problem can be inherited, but can also be caused by contracting particular viruses and the body’s response to them. As a result people with type 1 diabetes produce little or no insulin.

Question 39

What is type 2 diabetes?

Answer 39

Type 2 diabetes is caused by a person’s body becoming resistant to insulin. It can be controlled by diet and exercise. There is a link between rising levels of obesity and increasing levels of type 2 diabetes.

Question 40

How can type 1 diabetes be controlled?

Answer 40

-following a low sugar/carbohydrate diet
-injecting insulin
-possible transplant of pancreatic tissue

Question 41

What does the human nervous system consist of?

Answer 41

-the central nervous system (CNS) – the brain and spinal cord
-the peripheral nervous system – nerve cells that carry information to or from the CNS