Cells And Control

Question 1

Chromosomes

Answer 1

Are coiled up lengths of dna molecules

Question 2

Diploid

Answer 2

Two sets of chromosomes in a cell - 23pairs and 46

Question 3

Haploid

Answer 3

Half the number of chromosomes- 23

Question 4

Why is mitosis important?

Answer 4

We need to repair our cells
Help us grow
Asexual reproduction

Question 5

What is interphase?

Answer 5

The cell increases the amount of sub cellular structures

It then duplicates its dna

Question 6

What is prophase?

Answer 6

Spindle fibres start to form in the cell and the nuclear membrane starts to break down

Question 7

What is metaphase?

Answer 7

The chromosomes line up in the centre of the cell

Question 8

What is anaphase?

Answer 8

The spindle fibre pull the chromosomes apart.

Question 9

What is telophase?

Answer 9

The nuclei start to reform

Question 10

What is cytokinesis?

Answer 10

The cytoplasm and the cell membrane divide the two separate cells

Question 11

What is the formula to calculate multiple divisions of mitosis?

Answer 11

Number of cells = 2n
N = number of divisions

N = to the power of

Question 12

Cell differentiation

Answer 12

The process by which a cell changes to become specialised for its job. Having specialised cells allows multicellular organismsto work more efficiently.

Question 13

Cell division

Answer 13

Mitosis

- for growth in plants

Question 14

Cell elongation

Answer 14

Where a plant cell expands, making the cell bigger and so making the plant grow.

Question 15

What are stem cells?

Answer 15

Are cells that can turn into different types of cell - they are undifferentiated

Question 16

What are embryonic stem cells?

Answer 16

They are found in a human embryo.

They can become almost any cell type in the body - they are pluripotent

Question 17

What are the benefits of embryonic stem cells?

Answer 17

They can become any cell type in the body
Easy to remove
We can treat lots of diseases with them

Question 18

Drawbacks of embryonic stem cells

Answer 18

Religious issues - people believe that life starts at fertilisation therefore it’s murder
Money spent on this research can be spent somewhere else

Question 19

Risks of using embryonic stem cells

Answer 19

Can be rejected by the patient

Question 20

What are adult stem cells?

Answer 20

They are found in adults but they’re only found in certain places like bone marrow or in a certain places in the body with differentiated tissues.
They can only become a limited range of cell types
They are multi potent

Question 21

Benefits of adult stem cells

Answer 21

Can still treat certain disease

No ethical issues

Question 22

Drawbacks of adult stem cells

Answer 22

Limited amount of cells that they can become

Difficult to find and collect from adult tissues

Question 23

Risks of adult stem cells

Answer 23

Can be rejected by the patient

Question 24

Where are meristems found in plants?

Answer 24

Meristem tissue is found in the areas of a plant that are growing eg the tips of the roots and shoots

Question 25

What do meristems produce?

Answer 25

Unspecialised cells that are able to divide and form any cell type in the plant They can divide and differentiate to generate into any type of cell as long as the plant lives

Question 26

Example of how doctors use stem cells in medicine

Answer 26

They use them to cure sickle cell anaemia which can sometimes be cured with a bone marrow transplant

Question 27

What are receptors?

Answer 27

Groups of cells that detect a change in the environment

Question 28

What is a stimuli?

Answer 28

A change in the environment

Question 29

What does the cns control?

Answer 29

The body’s response to a stimulus

Question 30

What does the pns do?

Answer 30

Connects the sense organs to the cns using nerves

Question 31

Describe a motor neurone

Answer 31

Many short dendrites carry impulses from the cns to the cell body One long axon carries nerve impulses from the cell body to effector cells

Question 32

How can you tell if it is a motor neurone?

Answer 32

Nervous impulse is going towards the effector to bring about a response

Question 33

Describe a sensory neurone

Answer 33

One large dendron carries nerve impulses from receptor cells to the cell body which is located in the middle of the neurone One short axon carries nerve impulses from the cell body to the cns

Question 34

How can you tell that it is a sensory neurone?

Answer 34

Nervous impulse is going away from the sensory organ towards the cns

Question 35

Dendrites

Answer 35

Carry nerve impulses towards the cell body

Question 36

Axon

Answer 36

Carry nerve impulses away from the cell body

Question 37

What are the main functions of the myelin sheath?

Answer 37

It speeds you the nerve impulses as it travels along the dendron It insulated the electrical message

Question 38

role of the neurotransmitters

Answer 38

The electrical message travelling along the axon, reaches the end of the neurone Neurotransmitters are released from the end of the neurone This chemical message travels across the synapse This passes on the electrical message to the next neurone

Question 39

Reflex reactions

Answer 39

They are fast automatic responses that bypass the brain - they help protect us from injury

Question 40

What are synapses?

Answer 40

The connection between two neurones

Question 41

How do synapses connect neurones?

Answer 41

The nerve signal is transferred by chemicals called neurotransmitters which diffuse across the gap The neurotransmitters then set off a new electrical signal in the next neurone The transmission of a nervous impulse is fast but is slowed down by the synapse because the diffusion of neurotransmitters across the gap takes time

Question 42

Describe the pathway of a nerve impulse through a reflex arc

Answer 42

The eye detects a stimulus The sensory neurone sends a message to the spinal cord The nerve impulses from the sensory neurone cross the synapse and trigger the relay neurone The impulses are detected by the synapse which then cross the motor neurone It then travels to the effector which causes a response

Question 43

Normal cns

Answer 43

Slower response | Includes brain

Question 44

Reflex arc

Answer 44

Faster responses Does not go to the brain Relay neurone

Question 45

Both reflex and normal neurones

Answer 45

``` Sensory neurone Motor neurone Stimulus response Synapse Receptor cells Effector ```