Bio revision Flashcards
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What is auxin
Plant growth hormone
why do farmers use selective breeding
improve milk yield, disease resistance
where is auxin produced
roots and shoots
causes cells of plant shoots to elongate
What do auxins do when exposed to light
diffuse away from the light
Side with more auxin elongates faster
Difference between natural selection and selective breeding
ns is the favourable characteristics suited to the environment (longer)
Sbr is desired characteristics chosen by humans (takes less time)
what is fermentation
in the absence of o2 cells can’t undergo aerobic respiration
pyruvate produced in glycosis
converted into other compounds
metabolic process which allows cells to produce atp
what happens during fermentation
molecule of glucose is broken into 2 molecules of pyruvate produces atp and nadh
how is bread made (6)
yeast glucose- ethanol+co2
water activates yeast and hydrated flour
co2 causes dough to rise
sugar acts as food for yeast stimulating growth
high temps kill yeast in oven halting fermentation
trapped co2 bubbles cause dough to expand too
what is the cell cycle
growth, ,mitosis= division
process of mitosis
chromosomes in cell line up and split to different sides
cell membrane and cytoplasm split into 2 daughter cells
what is mitosis used for
growth, development, repair
what is meiosis
produces gametes (haploid cells)
what happens during meiosis
dna is replicated
cell divides twice into 4 genetically unique cells
how homeostasis works
receptors detect the change
co ordination centres interpret change
effectors carry out change (normally muscles or glands)
eg of homeostasis and feedback
glucose levels too high
decrease levels using insulin
if decreased too much, increase back
