EQ's

Question 1

A student was investigating the effect of light intensity on the rate of photosynthesis

Why did the student wait 5 minutes before taking a reading at each distance?

[1 mark]

Answer 1

To allow the pondweed to acclimatise to the conditions

Question 2

Suggest a reason why a student may not record results for distances closer than 10cm when investigating the effect of light intensity on the rate of photosynthesis?

[2 marks]

Answer 2

The light source emits heat which will warm the water

Too much heat affects the temperature which will affect the rate of photosynthesis

Question 3

Explain why the number of oxygen bubble released may remain constant while the distnace between the pondweed and the light source is still quite close

[1 mark]

Answer 3

Light is no longer the limiting factor

but then, when the distance INCREASES, light IS the limitng factor, you know this because the number of oxygen bubbles starts DECREASING!!!

Question 4

Explain how a farmer can enhance levels of light intensity inside a greenhouse

[1 mark}

Answer 4

Use artificial lighting in the dark/in winter

Question 5

Explain how a farmer can enhance levels of temperature inside a greenhouse

[1 mark]

Answer 5

Use a heater

Question 6

Describe two uses for mammals of the energy released by respiration

[4 marks]

Answer 6

1. Muscle contraction for movement
2. Synthesise Protein for growth

+ to keep warm

Question 7

Suggest one advantage of anaerobic respiration despite the fact that it releases less energy than aerobic respiration

[1 mark]

Answer 7

It releases energy more quickly

Question 8

A higher breathing rate is beneficial to excercising muscles

Explain why

[2 marks]

Answer 8

A higher breathing rate supplies the muscle cells with the sufficient volume of oxygen required for aerobica respiration which releases alot of energy

Muscle cells contract which requires energy, energy is released by respiration so:

Question 9

During prolonged exercise, the muscle’s reserves of glycogen become lower.

Explain why

[2 marks]

Answer 9

The glycogen is broken down
Into glucose
Which is oxidised for aerobic respiration

Question 10

What is the source of energy for photosynthesis?

[1 marks]

Answer 10

The Sun

Question 11

A lack of magnesium csn cause chloroplasts not to make enough chlorophyll.
Explain the effect that this would have on the rate of photosynthesis of a plant

[2 marks]

Answer 11

It would reduce the rate of photosynthesis
As the lack chlorophyll means that an insufficient amount of light energy will be absorbed

Question 12

Suggest a way that farmers can improve their heat conditions for photosynthesis in a greenhouse
And explain the effect that this would have on the rate of photosynthesis

[2 marks]

Answer 12

Add a heater
This will increase the temperature which will increase the rate of photosynthesis

Question 13

Suggest a way that farmers can improve their light intensity conditions for photosynthesis in a greenhouse
And explain the effect that this would have on the rate of photosynthesis

[2 marks]

Answer 13

Use artificial light
This will increase the rate of photosynthesis

Question 14

Suggest a way that farmers can improve their carbon dioxide conditions for photosynthesis in a greenhouse
And explain the effect that this would have on the rate of photosynthesis

[2 marks]

Answer 14

Use an oil heater
This will release carbon dioxide which will increase the carbon dioxide concentration in the greenhhouse which will increase the rate of photosynthesis

Question 15

Creating the ideal conditions in a greenhouse costs money
Explain why it would still be beneficial for the farmer to do this

[2 marks]

Answer 15

It will increase their crop yeild
This will allow them to earn more money (profit) back

Question 16

A snail is placed inside a beaker
A student then measures the carbon dioxide concentration inside the beaker
Describe and explain the results they would see after 2 hours

[2 marks]

Answer 16

The concentration of carbon dioxide increases
Because the snail is respiring which releases carbon dioxide

Question 17

A doctor measured the levels of lactic acid in an athletes muscles before,during and after excercise
Explain why the doctor will see an increase of lactic acid in the atheletes muscles during exercise

[3 marks]

Answer 17

After vigourous exercise,there is no longer a sufficient supply of oxygen,

this means that the glucose in the athletes cells is incompletely oxidised and anaerobic respiration occurs

This produces lactic acid

Question 18

What physical effects does a long period of physical excercise have on muscles?

[2 marks]

Answer 18

It causes muscles to become fatigued

And so muscle cells don’t contract efficiently

Question 19

After exercise, a doctor saw that the lactic acid levels in an athletes muscle cells decreased
Explain how this lactic acid is cleared from the body

[2 marks]

Answer 19

Blood transports the lactic acid from the muscle cells to the liver
Where it is converted into glucose
This process requires oxygen

Question 20

Describe how energy for the photosynthesis reaction is gained by plants

[2 marks]

Answer 20

Light

Is absorbed
by the chlorophyll in the chloroplasts

Question 21

Suggest a reason for an anamoly in the practical investigating the effect of light intensity on the rate of photosynthesis

[2 marks]

Answer 21

The scale was misread

The temperature changed

The light was moved

any of the three

Question 22

Explain how a student should deal with an anomylous result when calculating a mean

[1 mark]

Answer 22

They should not include the anomaly in their calculation of the mean

Question 23

When the optimum temperature of an enzyme is exceeded explain why the rate of photosynthesis decreases

[1 mark]

Answer 23

The enzymes become denatured so the shape of the active site changes

Question 23

A leaf is left exposed to light for four days

Explain why after the four days, the leaf contains beoth glucose and starch

[2 marks]

Answer 23

Photosynthesis was occuring inside the leaf which produces glucose
The glucose is then converted into insoluble starch for storage

Question 24

**Explain** why there will be **no starch** found in a **leaf** that was **left** in the **dark** for **four days** | [**3 marks**]

Answer 24

There is **no light** for **photosynthesis** to take place so **no more glucose** is **produced** So the **stores** of **starch** are **converted back** into **glucose** And the **glucose** is used for **respiration**

Question 25

A **student** is **investigating glucose** and **starch production** in **plants** **Suggest** a way that the student could **expand their experiment** after having just looked at the effect of **light** | [**1 mark**]

Answer 25

Test **variegated leaves** **Test other species** of **plant** | either of them

Question 26

**How** does a **TMV** result in **yellow leaves** and **stunted growth**? | [**3 marks**]

Answer 26

The virus **damages cells** which causes them to become **discoloured** and **yellow** This means a **lack** of **chlorophyll**, meaning **less light energy** is **absrobed** which **reduces** the **rate** of **photodynthesis** This means that **less glucose** is **produced** for **synthesising proteins** for **growth** so growth is **stunted**

Question 27

**How** does a **magnesium ion deficiency** result in **yellow leaves** and **stunted growth**? | [**3 marks**]

Answer 27

**Magnesium** is used to **synthesise chlorophyll** which gives leaves their **green colour** A **lack** of **chlorophyll** means the leave turn yellow **and less light energy** is **absorbed** which **reduces** the **rate** of **photosynthesis** This means that **less glucose** is **produced** to **synthesise proteins** for **growth** so growth is **stunted**

Question 28

**How** does a **Rose Black Spot** result in **yellow leaves** and **stunted growth**?

Answer 28

Rose Black Spot cause leaves to develop **black/purple spots**, this causes the leaves to develop a **yellow colour** This means a **lack of chlorophyll**, which means **less light energy** is **absorbed** by the **by the chlorophyll** which **reduces** the **rate** of **photosynthesis** This **reduces** the **rate** of **glucose production** for **protein synthesis** for **growth** so growth is s**stunted**

Question 29

**How** does an **infecton** from **aphids result** in**stunted growth**? | [**2 marks**]

Answer 29

The **aphids remove** the **sugars** from the **phloem** This means that there is **not enough glucose** for **synthesisig proteins** for **growth** so growth is **stunted**