Auxins are plant hormones.

Auxin causes the shoot of a plant to grow towards light in a process called:

Name one other tropism and state the stimulus the plant responds to in the tropism named.

A student wants to investigate the effect of light on plant growth.

The student will do the experiment at school, and has access to laboratory equipment. 

The student also has:

• a lamp
• pots of seedlings
• scissors
• a ruler
• cardboard boxes with lids

Plan an investigation to show the effect of light on the growth of plant seedlings.

Include the variables of the experiment in your plan.

A student decided to investigate the directional growth of plant roots.

The student positioned the root of a plant horizontally in a dark room, and left it for 3 days.

Figure A shows the root on the day the student left it, and figure B shows the root after 3 days.

The growth of plant roots in response to the gravity is called:

Explain why there was a change in the direction of root growth.

Give two reasons why the ability to change direction is important for plant roots.

A plant pot was knocked over by a cat.

Figure A shows the plant pot immediately after being knocked over.

Figure B shows the plant pot a week later.

The growth of plant shoots in response to gravity is called:

Give two changes that occurred in the plant in the five days after being knocked over.

Explain the change in direction of shoot growth.

A student investigated growth responses in bean seeds.

The student placed a bean seed in a jar with a moist cotton ball. 

After the seed had started to grow, the student placed the jar on its side and placed it inside a dark cupboard as shown in the diagram below.

Sketch over the figure the below to show what the root and shoot will look like after three days in the dark cupboard.

Explain how hormones in the roots and shoots of the bean seeds caused this directional growth.

Many of the mangoes eaten in the UK are grown in Central America.

The mangoes are harvested when they are still green, and transported to the UK in cargo ships.

When they arrive, ethene is sprayed over the mangoes to ripen them before they are taken to shops and supermarkets around the country.

Describe the effect of ethene on the ripening of mangoes.

Which concentration of ethene should supermarkets use to ripen mangoes?

Explain your answer.

Describe other uses of plant hormones in crop production.

Do not refer to fruit ripening in your answer.

A group of students performed an experiment to investigate the growth of plant shoots in response to light.

The students grew seeds until short shoots appeared.

They then used aluminium foil to cover different parts of the shoots, and placed them next to a light source. 

The students put boxes over the shoots to keep out any other light.

What is the purpose of the aluminium foil?

Give two variables that the students should control in the investigation.

Complete the diagram below to show the appearance of shoots A, B and C after 3 days.

A hormone in the plant causes the growth response.

What is the name of this hormone?

Explain how phototropism in a plant shoot helps the plant to survive.

Plant hormones have many uses in agriculture.

What is the name of the plant hormone used in fruit ripening?

Which plant hormone is used to produce seedless fruit?

Some weed killers contain plant hormones.

Explain how plant hormones work as weed killers.

Auxin can stimulate or inhibit the growth of shoots and roots, depending on the concentration used.

The graph below shows the effect of different concentrations of auxin on the growth of shoots and roots.

Using data from the graph, provide:

• two conclusions that can be made about shoot growth
• two conclusions that can be made about root growth

Give one stimulus a plant root responds to.

Do not refer to light in your answer.

Explain the uses of auxins, gibberellins and ethene in the commercial production of plants and fruits.

Plants respond to environmental factors.

Describe how different environmental factors affect:

• the direction of growth of roots
• the direction of growth of shoots

In your answer you should refer to the role of plant hormones.