Cells and Control

Question 1

Cell cycle

Answer 1

Interphase, prophase, metaphase, anaphase, telophase, cytokinesis

Question 2

Mitosis

Answer 2

The production of two daughter cells, both with identical sets of chromosomes to the parent cell, and results in the formation of two genetically identical diploid body cells

Question 3

Why is mitosis important

Answer 3

Asexual reproduction, growth and repair

Question 4

Interphase

Answer 4

New sub-cellular structures made

Question 5

Prophase

Answer 5

Nucleus breaks down, spindle fibres form and chromosomes (two identical chromatids joined by a centromere) shorten and thicken

Question 6

Metaphase

Answer 6

Chromosomes line up along the equator and spindle fibres attach

Question 7

Anaphases

Answer 7

Fibres shorten, pulling the chromatids apart

Question 8

Telophase

Answer 8

Membrane forms around each of the two sets to form two nuclei

Question 9

Cytokinesis

Answer 9

New cell surface membranes form two new cells

Question 10

Pluripotent

Answer 10

Capable of differentiating into many different cell types

Question 11

Benefits and risks of using stem cells in medicine

Answer 11

Embryonic - B: can differentiate into any cell, used to treat diseases such as leukaemia, can potentially be reprogrammed into adult ask cells to avoid rejection. R: ethical issues arisen, only a certain time span to experiment on the embryos
Adult - B: can be used in bone marrow transplants to treat some diseases, less ethical issues. R: have to find a match, chance of rejection from immune system, continual stem cell division can cause cancer

Question 12

Central nervous system

Answer 12

Brain and spinal chord

Tells the body what to do and responds to stimuli

Question 13

Effectors

Answer 13

The muscles or glands which bring about the response

Question 14

Dendrites

Answer 14

In all neurones. Receive impulses from receptors

Question 15

Dendron/axon

Answer 15

Carries the impulse along the neurone
Dendron - towards cell body
Axon - away from cell body

Question 16

Myelin sheath

Answer 16

Fatty layer which insulates the dendron/axon and speeds up transmission. Acts as an electrical insulator and speeds up electrical impulses.

Question 17

Neurotransmission

Answer 17

The travelling of impulses (electrical signals from the neurones) in neurones

Question 18

Reflex arc

Answer 18

Stimulus, receptor, sensory, synapse, relay, synapses, motor, effector, response

Question 19

Sensory

Answer 19

Carry impulses from the receptor to the CNS

Question 20

Relay

Answer 20

Carry impulses from the CNS to motor neurones

• short neurones with dendrites but no dendrons
• axons and axon terminals

Question 21

Motor

Answer 21

Carry impulses from relay to effectors

• dendrites but no dendrons
• axons and axon terminals

Question 22

Synapse

Answer 22

Gap between neurones. Convert electrical energy from impulses to chemical energy (neurotransmitters) which diffuse and are detected by the next neurone to make a new electrical impulse.

Question 23

Reflexes

Answer 23

Rapid response to stimuli. Takes the impulse to the spinal chord and back to the effector rather than the brain to save time and trigger a quicker response

Question 24

Cerebellum

Answer 24

(Base of the brain), controls balance, coordination and muscular activity

Question 25

Medulla oblongata

Answer 25

(Where the spinal cord and brain meet together), controls unconscious activities such as heartbeats, breathing, blinking and reflexes

Question 26

Cerebrum (cerebral cortex)

Answer 26

Split into cerebral hemispheres, controls consciousness, intelligence, memory and language

Question 27

Meninges

Answer 27

Protective membranes which the brain is encased in

Question 28

CT scans

Answer 28

(Computed tomography) shows shapes and structures at different layers and points of view, X-ray beam moves around the head at various positions and measures how much is absorbed, this builds a 3D image that isn't obscured by other structures as the slices build up this image, this helps doctors see what's wrong with a patient by giving them a greater insight.

Question 29

PET scans

Answer 29

(Positron emission tomography), patient is injected with radioisotope drugs such as fluorine-18 into their blood, gamma rays are emitted then detected by scanners to produce multiple images to be analysed - more gamma rays, more active part of the brain

Question 30

Limitations in treating damage in the brain e.g. Brain tumours

Answer 30

They can cause death as they can squash areas of the brain and stop them working. Cells in the brain grow and divide uncontrollably or cancer cells from other parts of the body spread to the brain. Causes headaches, double vision, trembling and personality changes

Question 31

Ways of treating brain tumours

Answer 31

Chemotherapy, radiotherapy (gamma rays or beta emitters but could damage surrounding healthy cells), surgically removed. Might not work due to blood brain barriers that only allow certain substances to pass from the blood to the brain.

Question 32

Spinal cord damage limitations

Answer 32

Causes loss of feeling in lower limbs or quadriplegia because nerve damage reduces flow of information

Question 33

Treating spinal cord damage

Answer 33

Stimulating the muscles using electrical wires as there are no stem cells in the spinal cord that produce nerve cells (won't feel pain)

Question 34

Cornea

Answer 34

The transparent and convex (important for determining the direction of light through refraction) front part (outermost layer of the eye) of the sclera which lets light into the eye

Question 35

Sclera

Answer 35

The white outer layer of the eye. It is relatively tough and strong so the eyeball doesn't damage easily

Question 36

Iris

Answer 36

Pigmented (decides colours of the eye) so light cannot pass through. It controls the size of the pupil and how much light is let in by contracting and relaxing its muscles

Question 37

Lens

Answer 37

Transparent, bi-convex, flexible disc behind the iris attached by the suspensory ligaments to the ciliary muscles. Focuses the image. It's behind the iris (on the inner side of the eye).

Question 38

Retina

Answer 38

The lining of the back of the eye containing two types of photoreceptors cells (light sensitive layer) - cone and rod

Question 39

Rod cells

Answer 39

Sensitive to dim light and black and white, allows you to see shapes and work in low light conditions

Question 40

Cone cells

Answer 40

Allow you to see colour and work in daylight conditions

Question 41

Optic nerve

Answer 41

Bundle of sensory neurones at the back of the eye

Question 42

Blind spot

Answer 42

The point where the optic nerve leaves the eye as there is no retina. Unaware of it because the brain fills in the gap

Question 43

Why does eyesight worsen when you get older

Answer 43

The lens hardens as we get older meaning it cannot refract light or easily focus on close objects

Question 44

Close sighted

Answer 44

Distant looks blurred. Light is focused in front of the retina so images that land on the retina are out of focus and blurry. Lens is too curved or the eyeball is long. Treated with concave lens glasses to spread the light from distant objects before it reaches the eye

Question 45

Far sighted

Answer 45

Close objects appear blurry. Light is focused behind the retina so the image that lands on the retina is out of focus. Lens too flat and thin or short eyeball. Treated with convex lens glasses which brings the light rays together more before they reach the eye

Question 46

Cataracts

Answer 46

Cause: protein builds up in the lens of your eye making it cloudy. This prevents light clearly coming through the lens causing some loss of vision. New cells form on the outside of the lens and the older cells are compacted into the centre of the lens. Treated: surgery, change in diet, glasses with plastic lens

Question 47

Colour blindness

Answer 47

Cause: genetics (mainly in men), cone cells either sense red, green or blue light. No treatment