Co-ordination and response

Question 1

what is a nerve impulse?

Answer 1

an electrical signal that passes along nerve cells (neurons)

Question 2

what is the difference between the central nervous system and the peripheral nervous system?

Answer 2

the central nervous system is the brain and the spinal cord

the peripheral nervous system is every other part of the nervous system

Question 2

what is involuntary action?

Answer 2

an action completes without conscious thought

Question 3

describe the reflex arc

Answer 3

Sensory receptor recieves stimulus

The signal travels along a sensory neuron

The synapse at the end of the sensory neuron carries a message to the relay neurone

The signal travels along the relay neuron, transmitted to a motor neuron

The signal travels along the motor neurone

An effector recieves the signal and carries out a response.

Question 4

what is a reflex action?

Answer 4

a rapid response to a stimulus by an effector (muscle or gland)

Question 4

what is a synapse

Answer 4

A junction between two neurons

ensures that impulses travel in one direction only

Question 5

what is the cornea and what is its function?

Answer 5

the transparent layer in front of the eye that protects the eye from damage

Question 5

what are sense organs?

Answer 5

groups of cells that detect changes in the environment

Question 6

what is the iris and what is its function?

Answer 6

the coloured ring around the pupil that controls its diameter

Question 6

what is the pupil and what is its function?

Answer 6

the pupil is the hole in the middle of the iris that lets light into the eye

Question 6

what is the optic nerve and what is its function?

Answer 6

the nerve coming out the back of the eye that send signals to the brain

Question 7

what is the function of the lens?

Answer 7

the lens focuses the light rays onto the retina

Question 8

state the response of the eye to a bright light

Answer 8

the pupil decreases in diameter to let less light in

Question 8

state the response of the eye to a lack of light

Answer 8

the pupil increases in diameter to let more light in

Question 9

how does the eye focus on near objects?

Answer 9

• the ciliary muscles contract and the suspensory ligaments loosen
• the lens becomes thicker
• light is refracted more

Question 9

explain how the eye focuses on distant objects

Answer 9

• the ciliary muscles relax and the suspensory ligaments tighten
• the lens becomes thinner
• light is refracted less

The light from distant objects needs to be bent only weakly to focus on the retina. When looking at distant objects, the ciliary muscles relax, pulling in the suspensory ligaments which pull on the lens, stretching it thinner and bending light less strongly. This brings distant objects into
focus on the retina.

Question 10

where are the adrenal glands located?

Answer 10

behind the kidneys

Question 10

what is a hormone?

Answer 10

a chemical secreted by a gland into the blood that brings about an affect on one or more target organs

Question 11

what hormone do the adrenal glands secrete?

Answer 11

adrenaline

Question 12

where is the pancreas located?

what hormone does it secrete?

Answer 12

behind the stomach

insulin

Question 13

what hormone do the testes secrete?

Answer 13

testosterone

Question 14

what hormone do the ovaries secrete?

Answer 14

oestrogen

Question 15

when is adrenaline secreted

Answer 15

during fight or flight situations

during
- scary situations
- stressful situations
- exciting situations

Question 15

give 3 effects of adrenaline

Answer 15

• widens pupils
• increases heart rate
• increases breathing rate

Question 16

what does oestrogen do?

Answer 16

causes the uterus lining to thicken

Question 17

what does testosterone do ?

Answer 17

main male sex hormone involved in growth of testes and penis triggers many changes in males during puberty - hair growth, deeper voice, increased muscle mass

Question 18

what does insulin do in the body?

Answer 18

Insulin decreases the level of glucose in the blood. It causes the liver cells to change blood glucose into glycogen to be stored. glycogen (the carbohydrate stored in the liver) and glucose ( the sugar carried around in the blood).

Question 19

what is homeostasis

Answer 19

maintaining a constant internal environment

Question 20

give 2 processes involving the skin that cool the body down

Answer 20

1. sweating - cools the body by evaporation 2. vasodilation - allows blood to flow closer to the surface of the skin where it can cool

Question 21

describe the process of vasodilation?

Answer 21

- the body detects a rise in temperature - blood vessels supplying the capillaries at the skin surface dilate (the muscles in the vessels relax) - more blood flows closer to the skin where it can cool

Question 22

describe the process of vasoconstriction

Answer 22

- the body detects a drop in temperature - the blood vessels supplying the capillaries at the skin surface constrict (the muscles in the vessels contract less blood flows closer to the skin so less heat is lost to the surroundings

Question 23

what is phototropism and which part of the plant is positively phototropic?

Answer 23

its the growth of a plant towards a light source the shoots are positively phototropic - they grow towards the light source

Question 23

what is gravitropism and which part of the plant is positively gravitropic?

Answer 23

its the growth of a plant towards the pull of gravity the roots are positively gravitropic - they grow in the same direction as the pull of gravity

Question 24

explain how auxin controls shoot growth

Answer 24

auxin is made in the shoot tips of the plant and spreads through the plant it is unequally distributed in response to light and or gravity it stimulates cell elongation and the growth of the shoot on the side with most auxin