Cells and Control

Question 1

what are chromosomes made up of

Answer 1

DNA

Question 2

What is a centromere

Answer 2

holds the sister chromatids together and helps them seperate

Question 3

what do chromosomes control, what do they contain

Answer 3

the functions of cells, all instructions needed to build an adult from fertilised egg cells

Question 4

what are diploid cells

Answer 4

cells with 23 pairs of chromosomes

Question 5

what are haploid cells

Answer 5

cells with only one set of the 23 pairs,so 23 chromosomes aka gametes

Question 6

What is the anagram for mitosis

Answer 6

IPMATC

Question 7

what is interphase

Answer 7

when the cell is not dividing but is doubling the number of cell organelles, DNA is also replicated so only 1 copy for each cell

Question 8

what is prophase

Answer 8

when the strands of DNA in the nuclear membrane condense into 46 pairs of chromosomes.Nuclear membrane breaks down.Centriole copies itself and move to opposite poles of the cell

Question 9

metaphase

Answer 9

chromosomes line up in the centre of the cell known as the equator
moved by spindle fibres which extend out from the centrioles and connect to the sister chromatid centromeres

Question 10

anaphase

Answer 10

spindle fibres shorten,seperating the sister chromatids at the centromere
once seperated,daughter chromatids are pulled to opposite sides of the cell

Question 11

telophase

Answer 11

new nuclear envelope forms around each group of chromosomes to form 2 daughter nuclei in the parent cell cytoplasm

Question 12

cytokinesis

Answer 12

cytoplasm seperated to produce 2 genetically identical daughter cells with their own nucleus

Question 13

what does mitosis produce

Answer 13

2 genetically identical cells

Question 14

what is mitosis used in organisms for

Answer 14

growing to adult size, making more cells
repair of damaged tissue by creating more cells
assexual reproduction to generate identical clones

Question 15

what is an issue with clones

Answer 15

equally susceptible to the same selection pressures/diseases-no evolutionary potential

Question 16

what is a tumour

Answer 16

mass of undifferiatiated cells

Question 17

what is a cancerous tumour

Answer 17

tumour that can break away and move to other organs in the body

Question 18

how are cancers treated

Answer 18

surgery,chemotherapy,radiotherapy

Question 19

when are cells unspecialized

Answer 19

less than or equal to 16 cells total

Question 20

how do cells become specialized

Answer 20

by switching on the correct genes to make proteins to give them their specific shape+function

Question 20

what are meristems

Answer 20

places on plants which contain accumulations of undifferentiated stem cells where mitosis occurs

Question 21

where are meristems found

Answer 21

the apexes(tips of roots/shoots)
around the stems/trunk
in side/lateral buds

Question 22

phloem

Answer 22

cells that take sugar made from photosynthesis from the source(leaf) to sink(roots)

Question 22

what is xylem

Answer 22

dead cells w/o cytoplasm which make water flow upwards by transpiration

Question 23

what are totipotent stem cells

Answer 23

embryo of 1-16 cells that can differentiate into every type of specialized cell

Question 24

what are pluripotent stem cell

Answer 24

as cell number increases,stem cells change to become pluripotent to be able to differentiate inti most but not all types of cell

Question 25

what are adult multipotent stem cells

Answer 25

stem cells to allow repair to happen,can only differentiate into a small number of specialized cell type

Question 26

what are stimuli

Answer 26

changes in our environment

Question 27

why can stimuli be detected

Answer 27

because our bodies contain certain receptors

Question 28

What is the CNS

Answer 28

-central nervous system, composed of brain and spinal cord -Role is to co-ordinate and control the body+responses

Question 28

What is the PNS

Answer 28

peripheral nervous system -contains 2 different types of nerve cell 1,sensory neurone 2,motor neurone

Question 29

how many types of effector are there

Answer 29

2 muscles+glands

Question 30

what are axon terminals

Answer 30

communicate with effectors(muscles+glands) to cause a response

Question 31

what is the fatty sheath

Answer 31

layer made of myelin that electrically insulates the neurone and speeds up the rate of impulse travel

Question 31

explain synapse

Answer 31

1.electrical impulse transports to axon terminal 2. neurotransmitter released and diffuses down its concn gradient across the synaptic cleft 3.neurotransmitter binds to receptors on second neurone 4.new electrical impulse generated

Question 32

what do synapses do, why is this useful

Answer 32

-they slow down the passage of information 1.synapses ensure that impulses only travel in one direction 2.one neurone may pass an impulse to several others, synapse acts as a junction box

Question 33

why are reflexes important

Answer 33

they protect our body from harm by minimising its exposure/contact to harmful stimuli

Question 34

characteristics of reflex arcs

Answer 34

must be automatic(not a conscious decision) must be exceedingly fast

Question 35

what are the 2 factors that affect speed of impulse

Answer 35

1.presence of myelin sheath 2.diameter of axon, thicker axon carries info faster