Topic 2 Cells and Control

Question 1

Interphase (not actually mitosis)

Answer 1

DNA spread out in long string
Cell grows and increases amount of sub cellular structures
Duplicates DNA into X shaped chromosomes (each arm is exact copy)

Question 2

Prophase

Answer 2

Chromosomes condense and become short and fat
Nucleus membrane breaks down and chromosomes lie free in cytoplasm
Cell fibres start to form

Question 3

Metaphase

Answer 3

Chromosomes line up in middle of cell

Question 4

Anaphase

Answer 4

Cell fibres pull chromosomes apart

Each arm of chromosomes go to opposite end of cell

Question 5

Telophase

Answer 5

Membranes form around each sets of chromosomes that become nuclei of two new cells

Question 6

Cytokinesis

Answer 6

Cytoplasm and cell membrane divide to form two, genetically identical daughter cells

Question 7

Uses of mitosis

Answer 7

To grow or replace damaged cells

Use mitosis to reproduce (asexual reproduction) like strawberry plants

Question 8

Growth

Answer 8

Increase in size or mass

Question 9

Growth in animals

Answer 9

Happens by cell division
Grows when young and stop growing at full growth
Most cell division happens for repair at full growth
Cell differentiation lost at early age

Question 10

What is a tumour?

Answer 10

Damages or changes in cell’s DNA that result in uncontrolled cell division that creates a mass of abnormal cells

Question 10

Growth in plants

Answer 10

Happens by cell elongation
Cell division happens in meristems (tops of roots and shoots, contain stem cells)
Continue to differentiate throughout whole life

Question 11

When is a tumour considered a cancer?

Answer 11

When it starts to invade and destroy nearby cells

Question 12

What does 50th percentile line represent mean?

Answer 12

Shows the mass that 50% of babies will have reached at a certain age

Question 13

When a doctor might be concerned with a child’s growth?

Answer 13

When it moves up or down 2 percentile lines or more, is above the top percentile line or below the bottom percentile
When there is an inconsistent pattern (small baby with large head)

Question 14

3 measurements taken on percentile charts for babies

Answer 14

Weight, height and head circumference

Question 15

Where are stem cells found

Answer 15

In early human embryos - embryonic stem cell

In adults in bone marrow - adult stem cell

Question 16

Difference between adult and embryonic stem cell

Answer 16

Embryonic stem cells can become any specialised cell in the body but adult stem cells can only become some

Question 17

Advantages of stem cell treatment

Answer 17

Adult stem cells used to cure diseases through transplants e.g bone marrow transplants to produce new blood cells in sickle cell anaemia.
Embryonic stem cells may be able to be used to be stimulated to differentiate into specialised cells

Question 18

Risks of stem cell treatment

Answer 18

Transplanted cells can be rejected as body recognises them as foreign and triggers an immune response. Drug can be taken to suppress this but makes patient susceptible to disease
Tumor development - stem cells divide quickly so it can go out of control
Disease transmission if donor cells are infected
Ethical issues of harvesting human embryos - potential life

Question 19

Nervous system

Answer 19

Receptor detects a stimulus and convers to a electrical impulse
Sent along sensory neurones to the Central Nervous System (brain and spinal chord) where a response is coordinated and impulses in CNS travel through the CNS along relay neurone
CNS sens information to an effector (muscle or gland) along motor neurone and effector responds accordingly

Question 20

What is a neurone

Answer 20

A cell with a cell body that has long extensions that connect to other neurones
Dendrons and dendrites - carry impulses toward the cell body
Axons - carry impulses away from cell body to axon terminal to be passed to a dendrite in synapse
Neurones are very long to speed up impulse (synapses [connections] slow down impulses)

Question 21

Sensory neurone

Answer 21

One long dendron carries nerve impulses from receptor cells

One short axon carries nerve impulses from cell body to CNS

Question 22

Motor neurone

Answer 22

Many short dendrites carry nerve impulses from the CNS fo cell body
One long axon carries nerve impulse from cell body to effector cells
Covered by myelin sheath to insulate axon to speed up impulse and improve reaction time

Question 23

Relay neurone

Answer 23

Many short dendrites carry nerve impulses from sensory neurones to cell body
One axon carries nerve impulses from cell body to motor neurones

Question 24

Synapse

Answer 24

Connection between two neurones
Neurotransmitters transfer nerve signal
They diffuse across gap and set off a new electrical signal in next neurone
Slows down transmission of nerve signal because diffusion takes time
It is important because it means nerve signal can only travel one way

Question 25

Reflex

Answer 25

Automatic rapid response to stimuli to reduce chances of injury
Passage of neurones goes through spine or unconscious part of brain

Question 26

Reflex arc

Answer 26

Stimuli is detected by receptors and impulses are sent along a sensory neurone to a relay neurone in the CNS.
When impulse reaches a synapse between sensory neurone and relay, a neurotransmitter is triggered that causes impulses to be sent along the relay neurone.
Same between relay neurone and motor
Impulse to effector - quicker because you don’t have to think

Question 27

Example of reflex arc

Answer 27

In eye, bright light can damage it, do light receptors in eye can detect bright light and send message to sensory neurone to unconscious part of brain (relay neurone) to a motor neurone telling iris to contract

Question 28

Put brain stuff here

Answer 28

Brain