B4- The Rate Of Photosynthesis

Question 1

What is the role of light in photosynthesis?

Answer 1

Light provides the energy needed for photosynthesis

Light intensity directly affects the rate of photosynthesis until a certain point.

Question 2

What happens to the rate of photosynthesis as light intensity is increased?

Answer 2

The rate of photosynthesis increases steadily up to a certain point

Beyond this point, the rate will no longer increase due to limiting factors like temperature or CO2 levels.

Question 3

What is a limiting factor in photosynthesis?

Answer 3

A factor that restricts the rate of photosynthesis, which can be light, CO2, or temperature

When one factor is in excess, another factor becomes limiting.

Question 4

What happens if you plot the rate of photosynthesis against the distance of a lamp from the plant?

Answer 4

You get a weird-shaped graph

Accurate measurements of light intensity at the plant using a light meter are needed for a proper graph.

Question 5

What is the effect of too little carbon dioxide on photosynthesis?

Answer 5

It slows down the rate of photosynthesis

CO2 is one of the raw materials needed for photosynthesis.

Question 6

What occurs to the rate of photosynthesis as CO2 levels increase?

Answer 6

The rate increases up to a point, then flattens out

This indicates that CO2 is no longer the limiting factor when the graph levels off.

Question 7

What is the ideal temperature for enzymes involved in photosynthesis?

Answer 7

The temperature must be just right, typically not too low or too high

Enzymes work slowly at low temperatures and can be damaged at high temperatures.

Question 8

What happens to enzymes at temperatures around 45 °C?

Answer 8

Enzymes needed for photosynthesis and other reactions will be damaged

This temperature is considered too hot for most outdoor conditions.

Question 9

Fill in the blank: If light and CO2 are in plentiful supply, the limiting factor must be _______.

Answer 9

temperature

Question 10

True or False: Increasing light intensity will always increase the rate of photosynthesis.

Answer 10

False

After a certain point, increasing light intensity does not further increase the rate.

Question 11

What is one way to change light intensity in a lab experiment?

Answer 11

By moving a lamp closer to or further away from the plant

This is a common method used to observe the effects of light on photosynthesis.

Question 12

What is the effect of light intensity on the rate of photosynthesis?

Answer 12

As light intensity increases, the rate of photosynthesis increases steadily until it levels off, indicating a limiting factor.

The graph shows that at higher temperatures, the rate levels off at a higher point, indicating temperature as a limiting factor.

Question 13

At what temperature does the line for photosynthesis level off at a higher point?

Answer 13

25 °C

This indicates that temperature was a limiting factor at 15 °C.

Question 14

How does CO2 concentration affect the rate of photosynthesis?

Answer 14

The line at a higher CO2 concentration (0.4%) levels off at a higher point than at 0.04%, indicating that CO2 concentration was a limiting factor at 0.04%.

Light intensity was constant in this scenario.

Question 15

What organism can be used to measure the effect of light intensity on photosynthesis?

Answer 15

Canadian pondweed

The rate of oxygen production by the pondweed corresponds to its rate of photosynthesis.

Question 16

What is the relationship between oxygen production and photosynthesis?

Answer 16

The faster the rate of oxygen production, the faster the rate of photosynthesis.

This is because the oxygen produced is a direct product of the photosynthesis process.

Question 17

What is the first step in the experiment using Canadian pondweed?

Answer 17

Place a source of white light at a specific distance from the pondweed.

This distance can affect the light intensity and thus the rate of photosynthesis.

Question 18

What is measured to determine the rate of photosynthesis in the pondweed experiment?

Answer 18

The length of the gas bubble collected in the capillary tube.

This length is proportional to the volume of oxygen produced.

Question 19

What should be controlled in the pondweed experiment?

Answer 19

Temperature and time the pondweed is left to photosynthesize.

Controlling these variables ensures accurate results.

Question 20

How can the experiment be repeated to measure different factors affecting photosynthesis?

Answer 20

By changing the distance of the light source or altering the temperature or CO2 concentration.

For example, a water bath can be used to set a specific temperature.

Question 21

Fill in the blank: The rate of photosynthesis can be expressed as the length of the bubble per _______.

Answer 21

unit time, e.g. cm/min.

This allows for comparison of results at different light intensities.

Question 22

What happens to light intensity as the distance from the light source increases?

Answer 22

Light intensity decreases as distance increases

This reflects the inverse relationship between distance and light intensity.

Question 23

What is the inverse square law?

Answer 23

Light intensity is inversely proportional to the square of the distance

This means if the distance doubles, the light intensity is four times smaller.

Question 24

How does halving the distance from the light source affect light intensity?

Answer 24

The light intensity becomes four times greater

This illustrates the principle of the inverse square law.

Question 25

If the distance is tripled, how does light intensity change?

Answer 25

Light intensity becomes nine times smaller

This is a direct application of the inverse square law.

Question 26

What is the formula to calculate light intensity using the inverse square law?

Answer 26

Light intensity = 1/d^2

Here, ‘d’ represents the distance from the light source.

Question 27

What does ‘a.u.’ stand for in the context of measuring light intensity?

Answer 27

arbitrary units

This is a unit of measurement used for light intensity.

Question 28

What is the primary purpose of a greenhouse in farming?

Answer 28

To create an ideal environment for plant growth

Greenhouses trap heat and control temperature for optimal growth conditions.

Question 29

How do farmers maintain temperature in a greenhouse during winter?

Answer 29

By using heaters

This helps keep the temperature at an ideal level for plant growth.

Question 30

What method do farmers use to provide additional light for photosynthesis at night?

Answer 30

They supply artificial light

This extends the time plants can photosynthesize effectively.

Question 31

How can carbon dioxide levels be increased in a greenhouse?

Answer 31

By using a paraffin heater

The burning paraffin produces carbon dioxide as a by-product.

Question 32

What benefit does keeping plants in a greenhouse provide regarding pests and diseases?

Answer 32

It makes it easier to keep them free from pests and disease

Controlled environments reduce exposure to harmful organisms.

Question 33

What role do fertilizers play in plant growth within a greenhouse?

Answer 33

They provide essential minerals for healthy growth

Fertilizers are crucial for nutrient management in plant cultivation.

Question 34

Why is it important for farmers to manage conditions in a greenhouse carefully?

Answer 34

To avoid wasting money while ensuring optimal plant growth

Over-supplying heat, light, or nutrients can lead to unnecessary costs.