5 interactive labs · AS & A Level Biology 9700
· Separate leaf pigments by chromatography and calculate Rf values, then read absorption and action spectra as you change the wavelength.
Separate leaf pigments by chromatography and calculate Rf values, then read absorption and action spectra as you change the wavelength.
You will be able to
Syllabus learning outcomes: 13.1.4, 13.1.5, 13.1.6
· Step through cyclic and non-cyclic photophosphorylation on a thylakoid membrane, then change the light and the route and trace where the oxygen comes from.
Step through cyclic and non-cyclic photophosphorylation on a thylakoid membrane, then change the light and the route and trace where the oxygen comes from.
You will be able to
Syllabus learning outcomes: 13.1.1, 13.1.3, 13.1.7, 13.1.8, 13.1.9, 13.1.10
· Follow labelled carbon atoms through fixation, reduction and regeneration, then switch off the light or the CO₂ and predict what happens to GP and RuBP.
Follow labelled carbon atoms through fixation, reduction and regeneration, then switch off the light or the CO₂ and predict what happens to GP and RuBP.
You will be able to
Syllabus learning outcomes: 13.1.2, 13.1.11, 13.1.12
· Change light intensity, CO₂ concentration and temperature one at a time, record response curves, and find which stage of photosynthesis is the bottleneck.
Change light intensity, CO₂ concentration and temperature one at a time, record response curves, and find which stage of photosynthesis is the bottleneck.
You will be able to
Syllabus learning outcomes: 13.2.1, 13.2.2
· Compare an aquatic plant and a DCPIP chloroplast suspension: set controls, repeat runs, and read means and 95% confidence intervals.
Compare an aquatic plant and a DCPIP chloroplast suspension: set controls, repeat runs, and read means and 95% confidence intervals.
You will be able to
Syllabus learning outcomes: 13.2.3, 13.2.4
Each link is a piece of biology that carries an idea from one lab into another. Follow one to use what you found here in a new setting.
A bean plant grows in soil that dries out over a hot, windy afternoon. Follow the water from the soil to the leaf and work out what happens to its photosynthesis.
The soil solution's water potential falls below that of the root hair cells. Which way does water now move?
Water still moves from higher to lower water potential, so less water, or none, enters the root hair cells; if the soil is lower still, water leaves them.
Transpiration continues from the leaves while uptake falls. What happens to the tension in the xylem water column?
Evaporation from the leaf keeps pulling on the cohesive column, so the tension rises while less water enters at the root: the plant loses water faster than it takes it up and the leaf cells lose turgor.
Abscisic acid reaches the guard cells. What happens to the stomata, and through which signal?
ABA triggers a rise in calcium ions as a second messenger; ions leave the guard cells, their water potential rises, water leaves by osmosis, turgor falls and the stomata close, reducing water loss.
The light is bright but the stomata are now nearly closed. What limits the rate of photosynthesis?
Carbon dioxide concentration inside the leaf falls, so it becomes the limiting factor: brighter light would barely raise the rate.
With less sucrose made in the leaves, what happens to translocation to the roots and seeds?
Less sucrose is loaded at the source, so the hydrostatic pressure gradient to the sinks is smaller and mass flow to them slows.
