b1: cell biology Flashcards
how does is sperm adapted to do job
long tail and many mitochondria
how does a tail help sperm
helps it swim towards egg
how does mitochondria help sperm
releases energy in respiration
what is a μm
micrometre
how many μm (micrometres) in a millimetre
1000
why is the incubator for growing bacteria set at 25 degrees
if any higher, risk of pathogen growth
how does only lifting the lid of the petri dish a little while growing bacteria effect the experiment
fewer bacteria can enter/leave
why do human skin cells need to divide
growth/ repair
replacing cells
what is a cell separated from an embryo and grown in a solution
stem cell
why is it necessary for cells to absorb nutrients by active transport
if its against a concentration gradient
why do cells need mitochondria
for energy from respiration
what is the function of muscle cells in the stomach wall
contracts to churn and mix food
describe differences btw how genetic material is arranged in prokaryotic vs eukaryotic cells
(bacteria have…)
- only 1 chromosome
- circular
- may have plasmids
- no nucleur
why dont single celled organisms need complex structures for gass exchange
larger sa:volume ratio
shor diffusion distance
diffusion via cell membrane is sufficient
what is translocation
movement of sugars
what equipment is used to prepare cells to be viewed under a microscope
- slide
- cover slip
- dye / stain
- (mounted) needle
- pipette / dropper
- scalpel
- forceps / tweezers
how has a red blood cell specialised
- no nucleus
- contains haemoglobin
- very small
- is a bioconcave disc
why does a red blood cell burst in water
water enters cell through osmosis as rbc has no cell wall so it swells and bursts
what cell in the leaf controls rate of water loss
guard cells
what is the structure of xylem
- made of dead cells
- is hollow
- tubular
- contains lignin
what is the structure of phloem
- has pores in end walls
- contains cytoplasm
- tubular
- made of cells
what is function of xylem
- transports water/ mineral ions
- involved in transpiration
- unidirectional
what is the function of phloem
- transports sugars
- involved in translocation
- bidirectional
why is water loss lower at midnight
stomata are closed because there is less light
what happens in stage 1 of the cell cycle
- DNA replicates
- sub-cellular structures increase in number
what happens in stage 2 of the cell cycle
one set of chromosomes is pulled to each side of the cell
what happens in stage 3 of the cell cycle
cytoplasm and membrane divide to form 2 daughter cells
why might a population of bacteria die out
- lack of space /competition
- build up of toxins
- temp too high
why is water uptake in a plant higher on a hot day
plant loses more water
more transpiration
more water must be taken up by roots
