Biology Worksheet-1

Name:________________________ Grade:9 Sec: A&B Date:__________

1 Fig. 1.1 shows the marine iguana, Amblyrhynchus cristatus

Fig. 1.1
(a) (i) Marine iguanas are reptiles.
State two features that are used to classify animals as reptiles.
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(ii) State two structures that are present in plant cells that are not present in the cells of
reptiles.
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(b) Marine iguanas feed on seaweed. Seaweed contains starch.
(i) State the names of two parts of the digestive system where starch is digested by
enzymes.
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(ii) Explain why the shape of an enzyme is important for digestion.

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3 (a) Digestive enzymes are secreted into the alimentary canal.
(i) As well as enzymes, other substances that are important for digestion are also secreted
into the alimentary canal.
State the names of two of these other substances.
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(ii) Table 2.1 summarises some facts about the enzymes that are secreted into the
alimentary canal. Complete Table3 .1.
Table 3.1

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(b) The activity of the enzyme pepsin was measured at different temperatures.
The results are shown in Fig. 3.1.

Describe and explain the effect of temperature on the activity of pepsin.

Use the information in Fig. 3.1 to support your answer.
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(c) Lactase is another digestive enzyme, which is produced by human babies.
(i) Explain why lactase is important for the nutrition of young babies.
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(ii) Most people stop producing lactase when they become adults. If they drink milk, this
may give them diarrhoea.
Describe the symptoms of diarrhoea.
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(iii) Cholera can also cause diarrhoea.

Explain how the cholera bacterium causes diarrhoea.
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[Total: 18]

4 Fig. 5.1 shows two structures found in the human digestive system.

Fig. 4.1
(a) (i) Identify the type of tooth shown in the diagram.

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(ii) Name the outer layer of the tooth.

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(iii) Explain how the tooth and the salivary gland contribute to digestion in different ways.
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(b) The stomach wall produces different substances that are involved in digestion.
(i) Name two of these substances and explain how they are involved in digestion.
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(ii) A hormone called gastrin stimulates cells in the stomach wall to release the substances
involved in digestion. Some of the gastrin is produced in the duodenum.
State how this gastrin reaches the stomach.

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[Total: 11]

5 Glasshouses are designed to maximise crop plant yield.

(a) (i) Explain why carbon dioxide enrichment is used in many glasshouses to increase crop
plant yield.
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(ii) Suggest how the carbon dioxide concentration in a glasshouse can be enriched.
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(iii) Outline how carbon dioxide in a glasshouse moves into leaves.
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(b) Additional lighting is often installed in glasshouses in countries with temperate climates.
Table 5.1 summarises some of the factors that are considered by plant growers when
choosing the type of lamps to install in a glasshouse.
Table 5.1

(i) Calculate the percentage increase in the energy used by the metal halide lamp compared
to the energy used by the fluorescent lamp.
Give your answer to two significant figures.
Space for working.

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(ii) State which type of lamp has the highest light intensity output per unit of electrical energy
used.
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(iii) Some types of lamp release a lot of heat.

Explain the possible effects of excessive heat on the plants in a glasshouse.
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[Total: 12]

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