Topic 2 - Cells And Control

Question 1

Interphase

Answer 1

Increases the amount of subcellular structures eg mitochondria , ribosomes. DNA duplicate

Question 2

First stage of mitosis

Answer 2

Prophase - chromosomes condense, shorter. Membrane around nucleus breaks down and chromosomes lie in cytoplasm.

Question 3

Second stage of mitosis

Answer 3

Metaphase - spindle fibres attach to centromere. chromosomes line up in middle of cell

Question 4

Third stage of mitosis

Answer 4

Anaphase - spindle fibres shorten and pull chromatids apart to the poles of the cell.

Question 5

Fourth stage of mitosis

Answer 5

Telophase - membrane form around each set of chromosomes. These become the nuclei of the two new cells - nucleus has divided.

Question 6

Final stage of mitosis

Answer 6

Cytokinesis - cytoplasm and cell membrane divide to form two genetically identical diploid cells.

Question 7

Why is mitosis important?

Answer 7

Used for growth and repair and replace damaged cells. Some organisms use it for asexual reproduction eg plants.

Question 8

How many chromosomes does each cell have at the end of mitosis?

Answer 8

46 (diploid)

Question 9

How does cancer happen?

Answer 9

The rate which cells divide by in mitosis is controlled by genes. If there’s a change in one of the genes that controls cells division they start diving uncontrollably.

Question 10

Cell differentiation (animals & plants)

Answer 10

Cell changes to become specialised for its job. Allows multicellular organisms to work more efficiently.

Question 11

Cell division (animals & plants)

Answer 11

By mitosis

Question 12

Cell elongation (plants only)

Answer 12

Plant cell expands, cell gets bigger so plant grows

Question 13

What is a percentile chart?

Answer 13

Used to monitor growth so any problems highlighted can be seen.

Question 14

What are stem cells?

Answer 14

Cells that can differentiate into any type of cells. Important for the growth and development of organisms.

Question 15

What is the function of embryonic stem cells?

Answer 15

Have the potential to develop into any type of cell.

Question 16

Function of meristem in plants

Answer 16

Produce stem cells. The unspecialised cells go to form specialised tissues like the xylem and phloem

Question 17

What is the meristem?

Answer 17

Tissue found in areas of plan that are growing eg tips of the roots and shoots

Question 18

Benefits of using stem cells in medicine?

Answer 18

Able to replace cells which have been damaged by disease or injury. Eg Parkinson’s

Question 19

Risks of using stem cells in medicine

Answer 19

Tumor could develop as stem cells divide very quickly
Disease could be passed on as viruses live inside cells
Ethical issues as embryo has a potential human life

Question 20

Reflex arc order

Answer 20

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

Question 21

Function of the stimulus

Answer 21

Detects a change in the environment

Question 22

Function of the receptor

Answer 22

Receptors in skin detect change in environment eg heat

Question 23

Function of the sensory neurone

Answer 23

Electrical impulse travel along the sensory neurone to the spinal cord/CNS

Question 24

Function of the synapse (first one)

Answer 24

Neurotransmitters diffuse across the synapse

Question 25

Function of relay neurone

Answer 25

The impulse is passed to the relay neurone

Question 26

What happens at the second synapse?

Answer 26

Impulse travels across another synapse

Question 27

What happens at the motor neurone?

Answer 27

Impulses travel along a motor neurone via a synapse

Question 28

What happens at the effector?

Answer 28

Impulses passes to the muscle/effector

Question 29

What happens at the response?

Answer 29

Muscle / effector contracts eg moving hand away from hot pan

Question 30

When would the reflex arc be used?

Answer 30

In dangerous situations

Question 31

What is the role of the myelin sheath?

Answer 31

Acts as an electrical insulator, speeds up impulse.

Question 32

What is an advantage on long neurones?

Answer 32

Speeds up the impulse

Question 33

What is the role of neurotransmitters?

Answer 33

Chemicals which diffuse across the gap between two neurones. The neurotransmitters then set off new electrical signal in the next neurone.