Plant structures and Their Functions Flashcards

(46 cards)

1
Q

What happens during Photosynthesis?

A

Photosynthetic organisms, such as green plants and algae, use energy from the sun to make glucose.

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2
Q

Some of the glucose is used to make…

A

larger, complex molecules that the plants or algae need to grow. Make up the organisms biomass.

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3
Q

How are photosynthetic organisms the main producers of food?

A

The energy stored in the organisms biomass then works its way through the food chain as animals eat them and each other.

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4
Q

What is the equation of photosynthesis?

A

Carbon dioxide + Water -> Glucose + Oxygen
Uses light energy.

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5
Q

Is photosynthesis exothermic or endothermic?

A

Endothermic as energy is taken in during the reaction.

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6
Q

What 3 factors affect the rate of photosynthesis?

A

Light intensity, the concentration of CO2 and the temperature.

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7
Q

What is a limiting factor?

A

It stops photosynthesis from happening any faster

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8
Q

As light level is raised…

A

the rate of photosynthesis increases steadily. Only true up to a certain point.

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9
Q

Beyond the certain point the light intensity will not…

A

make any difference - it will either be the temperature or the CO2 level which is the limiting factor.

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10
Q

How can you investigate light intensity in a lab?

A

By moving a lamp closer to or further away from your plant.

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11
Q

If you just plot the rate of photosynthesis against “distance of lamp from the plant”…

A

you get a weird-shaped graph.

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12
Q

The distance from the lamp and light intensity are…

A

inversely proportional. This means as the distance increases, the light intensity decreases.

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13
Q

What is the inverse sqaure law?

A

light intensity is proportional to 1/(distance)^2

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14
Q

The inverse square law means that…

A

if you halve the distance, the light intensity will be four times greater.

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15
Q

Increasing the CO2 concentration increases…

A

the rate of photosynthesis up to a point.

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16
Q

If temperature is the limiting factor…

A

its because its too low.

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17
Q

The enzymes needed for photosynthesis work more slowly at…

A

low temperatures.

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18
Q

What happens if the plant gets too hot?

A

The enzymes it needs for photosynthesis and its other reactions will be denatured. This happens at about 45 degree celsius.

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19
Q

Why do plants have millions of microscopic root hairs?

A

It gives the plant a large surface area for absorbing water and mineral ions from the soil.

20
Q

What are Phloem tubes made of?

A

Columns of elongated living cells with small pores in the end walls to allow stuff to flow through.

21
Q

What do Phloem tubes transport?

A

Food substances made in the leaves to the rest of the plant for immediate use or for storage.

22
Q

What is this process of transporting food substances called?

A

Translocation

23
Q

What does Translocation require?

A

Energy from respiration.

24
Q

In Phloem tubes, does the transport go in both directions?

25
What are xylem tubes made of?
Made of dead cells joined end to end with no end walls between them and a hole down the middle.
26
Why doe Xylem tubes require Lignin?
Provides strength and support so allows the xylem to withstand pressure changes as water moves through the plant.
27
What do Xylem tubes carry?
Water and mineral ions from the roots to the stem and leaves.
28
What is Transpiration?
The movement of water from the roots, through the xylem and out of the leaves.
29
What is Transpiration caused by?
The evaporation and diffusion of water from a plants surface. Most transpiration happens at the leaves.
30
In transpiration the loss of water creates...
a slight shortage of water in the leaf, and so more water is drawn up from the rest of the plant through the xylem vessels to replace it.
31
What are Stomatas?
Tiny pores on the surface of a plant.
32
Where is a stomata found?
On the lower surface of the leaf.
33
What do Stomata allow?
CO2 and Oxygen to diffuse directly in and out of a leaf. Also allow water vapour to escape during transpiration.
34
What are Stomata surrounded by?
Guard cells, which changes shape to control the size of the pore.
35
When the guard cells are turgid (swollen with water)...
the stomata are open.
36
When the guard cells are flaccid (low on water)...
the stomata are closed.
37
What are the 3 factors which affect Transpiration rate?
Light intensity, Temperature, Air flow.
38
The brighter the light...
the greater the transpiration rate.
39
Because photosynthesis can't happen in the dark...
the stomata does not need to be open to let CO2 in.
40
When the stomata are closed...
Very little water can escape.
41
The warmer it is...
the faster transpiration happens.
42
What happens to the water particles during transpiration when it is warmer?
Have more energy to evaporate and diffuse out of the stomata.
43
The better the air flow around a leaf...
the greater the transpiration rate.
44
What will water vapour do if air flow around a leaf is poor?
The water vapour just surrounds the leaf and doesn't move away. This means there's a high concentration of water particles outside as well as inside it, so diffusion doesn't happen as quickly.
45
How can you estimate Transpiration rate?
You can use a special piece of apparatus called a potometer.
46
What does potometer measure?
It actually measures water uptake by a plant, but its assumed that water uptake by the plant is directly related to water loss from the leaves (transpiration).