5.1.1 Crop Plants: Glasshouses & Polythene Tunnels

Question 1

(Crop Plants: Glasshouses & Polythene Tunnels)
If a plant is given unlimited light, carbon dioxide and water and is at a warm temperature, the only thing limiting the rate at which it can photosynthesise is what?

Answer 1

Iits own ability to absorb these materials and make them react

Question 2

However, most often plants do not have unlimited supplies of these things, so their rate of photosynthesis is limited by what?

Answer 2

Whatever factor is the lowest at that time (known as the limiting factor)

Question 3

The three main factors that limit the rate of photosynthesis are what?

Answer 3

Temperature
Light intensity
Carbon dioxide concentration

Question 4

As temperature increases the rate of photosynthesis increases as the reaction is controlled by what?

Answer 4

Enzymes

Question 5

However, as the reaction is controlled by enzymes, this trend only continues up to a certain temperature beyond what?

Answer 5

Beyond which the enzymes begin to denature and the rate of reaction decreases

Question 6

The more light a plant receives, the faster the rate of what?

Answer 6

Photosynthesis

Question 7

This trend will continue until some other factor required for photosynthesis prevents what?

Answer 7

The rate from increasing further because it is now in short supply

Question 8

The knowledge about limiting factors and how they affect the rate of photosynthesis can be used by farmers to what?

Answer 8

Improve crop yields

Question 9

Growing crops outside does not allow farmers to control what?

Answer 9

Any of these factors

Question 10

Glasshouses and polythene tunnels provide an enclosed environment in which farmers can, to some extent, control the climate inside and what?

Answer 10

Increase their crop yields

Question 11

In a glasshouse, several conditions can be manipulated to increase the rate of what?

Answer 11

Photosynthesis

Question 12

How does artificial heating increase the rate of photosynthesis ?

Answer 12

(enzymes controlling photosynthesis can work faster at slightly higher temperatures – only used in temperate countries such as the UK)

Question 13

How does artificial lighting increase the rate of photosynthesis ?

Answer 13

(plants can photosynthesise for longer)

Question 14

How does increasing the carbon dioxide content of the air inside, increase the rate of photosynthesis ?

Answer 14

(plants can photosynthesise quicker)

Question 15

What are the 4 main conditions that can be manipulated to increase the rate of photosynthesis?

Answer 15

Artificial heating

Artificial lighting

Increasing carbon dioxide content

Regular watering

Question 16

When considering the use of glasshouses and manipulating conditions like this, farmers need to balance the extra cost of providing what, against the increased income?

Answer 16

Heating

lighting

carbon dioxide

Question 17

In tropical countries where temperatures are much hotter, glasshouses may still be used to control other conditions however they may need to be what, to release hot air?

Answer 17

Ventilated

Question 18

If temeratures rise too high, it could cause what?

Answer 18

The denaturation of the enzymes controlling the photosynthesis reaction

Question 19

Polythene tunnels, more commonly called polytunnels, are what?

Answer 19

These are large plastic tunnels that cover crops

Question 20

They can protect crops grown outside from what?

Answer 20

The effects of the weather, including

Excessive wind,
Rain
Extreme temperatures

Question 21

They also increase what, inside the tunnel?

Answer 21

The temperature slightly

Question 22

They can prevent the entry of pests that can do what?

Answer 22

Damage plants or diseases that can kill plants