b1: cell biology

Question 1

how does is sperm adapted to do job

Answer 1

long tail and many mitochondria

Question 2

how does a tail help sperm

Answer 2

helps it swim towards egg

Question 3

how does mitochondria help sperm

Answer 3

releases energy in respiration

Question 4

what is a μm

Answer 4

micrometre

Question 5

how many μm (micrometres) in a millimetre

Answer 5

1000

Question 6

why is the incubator for growing bacteria set at 25 degrees

Answer 6

if any higher, risk of pathogen growth

Question 7

how does only lifting the lid of the petri dish a little while growing bacteria effect the experiment

Answer 7

fewer bacteria can enter/leave

Question 8

why do human skin cells need to divide

Answer 8

growth/ repair
replacing cells

Question 9

what is a cell separated from an embryo and grown in a solution

Answer 9

stem cell

Question 10

why is it necessary for cells to absorb nutrients by active transport

Answer 10

if its against a concentration gradient

Question 11

why do cells need mitochondria

Answer 11

for energy from respiration

Question 12

what is the function of muscle cells in the stomach wall

Answer 12

contracts to churn and mix food

Question 13

describe differences btw how genetic material is arranged in prokaryotic vs eukaryotic cells

Answer 13

(bacteria have…)
- only 1 chromosome
- circular
- may have plasmids
- no nucleur

Question 14

why dont single celled organisms need complex structures for gass exchange

Answer 14

larger sa:volume ratio
shor diffusion distance
diffusion via cell membrane is sufficient

Question 15

what is translocation

Answer 15

movement of sugars

Question 16

what equipment is used to prepare cells to be viewed under a microscope

Answer 16

• slide
• cover slip
• dye / stain
• (mounted) needle
• pipette / dropper
• scalpel
• forceps / tweezers

Question 17

how has a red blood cell specialised

Answer 17

• no nucleus
• contains haemoglobin
• very small
• is a bioconcave disc

Question 18

why does a red blood cell burst in water

Answer 18

water enters cell through osmosis as rbc has no cell wall so it swells and bursts

Question 19

what cell in the leaf controls rate of water loss

Answer 19

guard cells

Question 20

what is the structure of xylem

Answer 20

• made of dead cells
• is hollow
• tubular
• contains lignin

Question 21

what is the structure of phloem

Answer 21

• has pores in end walls
• contains cytoplasm
• tubular
• made of cells

Question 22

what is function of xylem

Answer 22

• transports water/ mineral ions
• involved in transpiration
• unidirectional

Question 23

what is the function of phloem

Answer 23

• transports sugars
• involved in translocation
• bidirectional

Question 24

why is water loss lower at midnight

Answer 24

stomata are closed because there is less light

Question 25

what happens in stage 1 of the cell cycle

Answer 25

• DNA replicates
• sub-cellular structures increase in number

Question 26

what happens in stage 2 of the cell cycle

Answer 26

one set of chromosomes is pulled to each side of the cell

Question 27

what happens in stage 3 of the cell cycle

Answer 27

cytoplasm and membrane divide to form 2 daughter cells

Question 28

why might a population of bacteria die out

Answer 28

• lack of space /competition
• build up of toxins
• temp too high

Question 29

why is water uptake in a plant higher on a hot day

Answer 29

plant loses more water
more transpiration
more water must be taken up by roots