Key Questions Part 3 Flashcards
(12 cards)
Describe how a student could estimate the mean length of onion cells on a slide
place ruler on (microscope) stage
* focus on (scale on) ruler
* measure diameter / width of field of view
* in millimetres
* replace ruler with slide
* focus on cells
* use same magnification
* estimate / count number of cells that fit (lengthwise) across field
of view
* (to calculate mean length of onion cells):
divide diameter / width of field of view by (estimated) number of
cells
or
divide diameter / width of field of view by 3 cells
Why should a student calculate the percentage change in mass for each piece of veg?
to control for the starting mass (not all same at start)
Why do carrots not change mass when boiled?
the (partially permeable / cell)
membrane was damaged
How could you accurately measure ohotosynthesis?
volume of gas produced
increased length of time
Why does temperature increase rate of photosynthesis?
the reaction is controlled by enzymes
Differences between sexual and asexual reproductions
Sexual - fusion of male and female gametes, variation in offspring, meiosis, more energy required, slower
Asexual - only one parent, no mixing of DNA, offspring are genetically identical/clones, mitosis, faster
Why do each type of lipase only act on one type of lipid molecule?
active site has specific shape
What can cause stunted growth and yellow leaves?
lack of sunlight
not enough glucose to make proteins for growth
Why would a plant float?
oxygen was produced in
photosynthesis
oxygen / gas is trapped in /
around disc / leaf
Why do companion cells help phloem cells?
cell contains mitochondria
for respiration
releases energy
helps more sugars against the concentration gradient
by active transport
How do nodules help bacteria?
obtain glucose for respiration
How are malarial protists and prokaryotic cells different?
no nucleus
protist has mitochondria
protists don’t have cell wall
