Plant responses

Question 1

Summary of Boysen-Jenson results

Answer 1

1) The factor causing phototropism moves away from the tip
2) The factor causing phototropism is not an electrical impulse
3) The factor causing phototropism moves away from light

Question 2

Auxin

Answer 2

-Auxin is synthesised at the tip of the shoot
-Causes cell to elongate on one side so stem bends
-Scientists originally thought auxin was destroyed by light
-This was disproved by plants grown in the dark and plants grown in unilateral light having similar auxin levels

Question 3

When evaluating claims involving graphs look at whether the graphs themselves are accurate and valid to support final conclusions

Answer 3

No numerical values on axis/ labels wrong way round/ no SD/ should be percentage increase in mass/ correlation is not evidence of causation/ risk of biased

No method given/ species type of plant is not named/ no control variables / conc of hormone / temp/ location/ water availability / pesticides/ herbicides

Question 4

had slightly shorter roots
grew taller
all began to grow within two days of each other
had fewer and shorter side branches
retained their fruit and leaves for longer.

Answer 4

Auxin: High auxin levels inhibit root growth

Taller: giberellins promote stem elongation by stimulating cell elongation and division

Growth timing: Giberellins promote seed germenation by activating genes for amylase and
protease enzymes, which break down food stores

Side branches: auxin maintains apical dominance and inhibits the growth of lateral shoots/ branches

Delayed fruit and leaf fall: Auxin slows down fruit drop and leaf fall. Auxin inhibits abscission by preventing ethene production

Question 5

What happens if the proton pump is inhibited

Answer 5

No chemiosmosis
Photophosphorylation stops
Less/ no ATP produced
Less/ no NADP produced
No calvin cycle
No TP
No respiratory substrate

Question 6

How is gibberellin a chemical messenger

Answer 6

Giberellin is a chemical messanger/ produced in one part of the plant but has effects in anpther part/

Affects activity of cells/ long-lasting periods/ wide spread affect

Question 7

What could different light intensities lead too

Answer 7

Could lead to variation in bending

Question 8

Plant chemical defences

Answer 8

Alkaloids - poisonous to insects
Tannins - bind to proteins in the animals liver making it harder to digest
Pheromones - a defence response in other nearby plants

Question 9

How does ethene cause other fruit to ripen

Answer 9

Ethene stimulates enzymes to break down the cell wall / breaks down chlorophyll / converts starch to sugars

Question 10

How to make a 50cm3 solution from 1000

Answer 10

Take 10cm3 from the 1000 solution and add 90 distilled water
=100
then 50 / 50 distilled