CB2a paper 1

Question 1

What does mitosis produce?

Answer 1

produces two new cells that are identical to each other, and to the parent cell.

Question 2

Mitosis: The process of growth an division?

Answer 2

The cell cycle

Question 3

Mitosis: cell cycle

Answer 3

Interphase
Diploid has two sets of chromosomes.
Each chromosome is copied, and they remain attached in ‘x’ shapes.

The copies of chromosomes separate. In each daughter cell, there is the same number of chromosomes as in the parent cell.

Question 4

Are gametes (sex cells) haploid or diploid?

Answer 4

Haploid

Question 5

Haploid

Answer 5

Contains one copy of each type of chromosome

Question 6

Diploid

Answer 6

Cells with two sets of chromosomes.

Question 7

What are the two phases of the cell cycle?

Answer 7

Interphase and

Cell division or mitosis.

Question 8

Interphase

Answer 8

Cell makes extra sub-cellular cell parts like mitochondria.

DNA replication - makes copies of all chromosomes. The copies of chromosomes stay attached, forming ‘x’shapes.

Question 9

Stages of mitosis

Answer 9

Prophase- nucleus starts to break down + spindle fibres appear.
Metaphase- by end of it, chromosomes are lined up on the spindle fibres, across the middle of the cell.
Anaphase- chromosome copies are separated and moved to either end of the cell, on the spindle fibres.
Telophase- a membrane forms around each set of chromosomes, to form nuclei.
Cytokinesis- cell surface membrane forms to separate the two cells. Cell walls form in plant cells.

Question 10

Prophase

Answer 10

Nucleus starts to break down + spindle fibres appear.

Question 11

Metaphase.

Answer 11

By end of it, chromosomes are lined up on the spindle fibres, across the middle of the cell.

Question 12

Anaphase

Answer 12

Chromosome copies are separated and moved to either end of the cell, on the spindle fibres.

Question 13

Telophase

Answer 13

A membrane forms around each set of chromosomes, to form nuclei.

Question 15

Asexual reproduction

Answer 15

Produces offspring that are clone, meaning cells have the same chromosome as patent cells. They are genetically identical.
So it relies on mitosis.
Much faster than sexual reproduction.
Does not produce variation, like sexual reproduction does.

Question 16

Cancer tumours

Answer 16

Changes in cells, sometimes can turn them into cancer cells, meaning that they can undergo uncontrollable cell division.
The repair cell division causes growing lumps of cells called tumours. These can result in damage to the body or even death.

Question 17

Growth

Answer 17

Increase in size as a result of increased number or size of cells.

Question 18

Differentiation

Answer 18

The process that changes less specialised cells into more specialised ones.

Question 19

Example of a specialised human cell.

Answer 19

Red blood cell.
No nucleus allowing more space for haemoglobin.
Large surface are, enabling diffusion of oxygen in and out, happens at a faster rate.

Nerve cells are another example. Can carry electrical impulses along a long fibre around the body.

Question 20

Meristems

Answer 20

Cells near the end of each shoot and root, allowing the plant to grow throughout its life.

Question 21

Elongation

Answer 21

Cells increasing in length.

Question 22

Percentage change calculation

Answer 22

Final value-start value
——————————- x100%
Starting value

Question 23

Stem cells

Answer 23

Cells that can divide repeatedly over a long period of time, that produce cells that then differentiate.

Question 24

Where are stem cells found in plants?

Answer 24

Meristems

Question 25

Cytokinesis

Answer 25

Cell surface membrane forms to separate the two cells. Cell walls form in plant cells.

Question 26

Nearly Amy specialised cell can be created by

Answer 26

Plant stem cells which differs from animals where only some can be.

Question 27

The cells of an early stage embryo are

Answer 27

Embryonic stem cells, that can produce any type of specialised cell.

Question 28

Adult stem cell

Answer 28

Can only produce the type of specialised cell that is around them in the tissue. The adult stem cells in humans allow them to replace old or damaged cells.

Question 29

Where are blood stem cells found

Answer 29

In marrow in the middle of long bones.they continue to divide to produce new blood cells.

Question 30

Stem cells offer a way of…

Answer 30

Treating many different diseases caused by damaged cells. They stimulate stem cells to make them produce the specialised cells that are needed and then injecting them in the places needed.

Question 31

Problems with stem cells

Answer 31

They can cause cancer, if they continue to divide in the body after they have replaced the damaged cells.
Rejection- stem cells from one person may be killed by the immune system of other people.

Question 32

Central nervous system

Answer 32

The brain and spinal cord form it, which controls the body.

Question 33

Impulses

Answer 33

Electrical signals.

Question 34

Stimulus

Answer 34

Anything your body is sensitive to.

Question 35

Sense organs examples

Answer 35

Eyes, ears, skin etc…

They contain receptor cells that detect a stimulus.

Question 36

Receptor cells

Answer 36

They create impulses, which usually travel to the brain. The brain then processes this information and can send impulses to other parts of the body to cause something to happen(a response).

Question 37

Neurotransmission

Answer 37

The travelling or transmission of impulses and happens in neurones (nerve cells).

Question 38

Neurones have…

Answer 38

A cell body and long extensions to carry impulses.

Question 39

Sensory neurone

Answer 39

Carries impulses from receptor cells, towards the CNS (central nervous system). A receptor cell impulse passes into a tiny branch called a dendrite. It is then transmitted along the dendron, and then an axon. A series of axon terminals allow impulses to be transmitted to other neurones.

Question 40

Why are dendrond and axons frequently long?

Answer 40

To allow fast neurotransmission over long distances.

Question 41

What is the fatty layer surrounding the dendron and axon called?

Answer 41

Myelin sheath.
It electrically insulates a neurone from neighbouring neurones, stopping the signal losing energy.
It also makes and impulse ‘jump’ along a cell Tweenies the gaps in the myelin, thus speeding up neurotransmission.

Question 42

When the brain coordinates a response to a stimulus, impulses are sent to…

Answer 42

Effectors, and theses carry out the action. They include muscle and glands.

Question 43

Motor neurones

Answer 43

Carry impulses to effectors. Don’t have a dendron. Dendrites are on cell body.

Question 44

Relay neurones

Answer 44

True neurones found in the spinal cord. They link motor and sensory neurones. Make up the a lot of the nerve tissue in brain too. Don’t have a dendron. Dendrites are on the cell body.

Question 45

Synapse

Answer 45

Tiny gap between neurones. When an impulse reaches an axon terminal, neurotransmitter substance is released into the gap. This is detected by the next neurone, generating a new impulse.Synapses slows down neurotransmission. They are however useful because they are only released from axon terminals and so impulses can only travel in one direction, allowing many fresh impulses to be generated in many neurones connected to one neurone- the original impulse does not need to be split and lose strength.

Question 46

Reflex

Answer 46

Controlled by the reflex arc. When the safety of an organism demands a very quick response, the signals may be passed directly from a sensory neuron, via a relay neurone, to a motor neurone for instant, unthinking action.

Question 47

Reflex arc

Answer 47

Is the nerve pathway which makes such a fast, automatic response possible. It is in-built, or innate, behaviour, and we all behave in the same way. It bypasses the parts of the brain, involved in processing information and so quicker than responses that need processing.