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Flashcards in Plantsss Deck (22):
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What is a tropism

The growth response of a plant to a directional stimulus

1

Hydrotropism in shoots

None

2

Hydrotropism in roots

Some grow towards direction of water (positive hydrotropism)

3

Phototropism in shoots

Grow towards light source (positive phototropism

4

Phototropism in roots

Most species show no response; some grow away from light (negative phototropism)

5

Geotropism in shoots

Grow against direction of gravity (negative geotropism)

6

Geotropism in roots

Grow towards direction of gravity (positive geotropism)

7

What is auxin

The hormone(plant growth substance) that is responsible for tropism

8

Why does a lack of nitrogen inhibit he growth of a plant

Nitrate ions needed For making amino acids which make proteins which are required for growth

9

Why are phosphate ions needed by plants

Making DNA
A plant deficient in phosphate will have poor root growth and younger leaves will turn purple

10

Why are potassium ions needed by plants

Needed for enzymes of respiration and photosynthesis to work
In plants lacking potassium, leaves turn yellow with dead spots

11

Why are magnesium ions needed by plants

Magnesium is needed for making chlorophyll for photosynthesis
The colour of this pigment is green and so plants that lack magnesium have yellow leaves

12

Why is starch a good way of storing carb

Not soluble
Compact
Can be broken down easily

13

Why can't you test a fresh leaf for starch using iodine

The waxy surface won't absorb the solution
Green colour of leaf masks colour change

14

How do you remove the outer waxy layer and decolorise a leaf

Place it in boiling ethanol

15

How can you de starch a leaf

Place it in the dark for 2 or 3 days
The plant uses up the starch stores in its leaves

16

How to stop co2 from getting to a plant

Place the plant in a closed container containing a chemical called soda lime - this absorbs co2 from the air around the plant

17

What does a clinostat do

Holds the plant and slowly rotates in a vertical plane, so that the movement eliminates any directional stimulus that may be acting on the seeds

18

Guard cell adaptation for function

'Banana' shape with thicker cell wall on inside (around) means that when the guard cells become turgid they change shape, bowing outwards, so opening the stoma for gas exchange

19

Only cells that don't need osmosis to maintain their shape

Xylem cells

20

preventing water loss by having stomata in sunken pits in leaf

A region of humid air is trapped in the pit
This reduces evaporation through the stomata, conserving water in the plant

21

Lipids uses

Energy store in some plants eg nuts, seeds
Part of all cell membranes