Nirmal Bhartia School
Life Processes – Revision worksheet
M.M 10
1.Why is the inner wall of the alimentary canal not digested although the digestive enzymes
can digest all the materials that make cells? 2
2. The two openings of the pharynx, one leading to trachea and the other leading to
oesophagus, lie very close to each other. Yet food we swallow normally does not enter into
our trachea. Why? 2
3. Which of the following statements about the autotrophs is incorrect?1
(a) They synthesise carbohydrates from carbon dioxide and water in the presence of sunlight
and chlorophyll
(b) They store carbohydrates in the form of starch
(c) They convert carbon dioxide and water into carbohydrates in the absence of sunlight
(d) They constitute the first trophic level in food chains
4. In which of the following groups of organisms, food material is broken down outside the
body and absorbed? 1
(a) Mushroom, green plants, Amoeba
(b) Yeast, mushroom, bread mould
(c) Paramecium, Amoeba, Cuscuta
(d) Cuscuta, lice, tapeworm
5. Select the correct statement. 1
(a) Heterotrophs do not synthesise their own food
(b) Heterotrophs utilise solar energy for photosynthesis
(c) Heterotrophs synthesise their own food
(d) Heterotrophs are capable of converting carbon dioxide and water into carbohydrates
6. Fermentation causes the dough to rise. Why does the dough rise? 1
a)
b)
c)
d)
The dough rises because alcohol is produced and turns into a gas.
The dough rises because of single-celled fungi reproducing in it.
The dough rises because a gas, carbon dioxide, is produced.
The dough rises because fermentation turns water into a vapour.
Case study
Tooth Decay- Bacteria that live in our mouths cause dental caries (tooth decay). Caries has
been a problem since the 1700s when sugar became available from the expanding sugarcane
industry. Today, we know a lot about caries. For example: Bacteria that cause caries feed on
sugar. The sugar is transformed to acid. Acid damages the surface of teeth. Brushing teeth
helps to prevent caries. The following graph shows the consumption of sugar and the amount
of caries in different countries. Each country is represented by a dot in the graph.
Which one of the following statements is supported by the data given in the graph? 2
A .In some countries, people brush their teeth more frequently than in other
countries.
B The more sugar people eat, the more likely they are to get caries.
C.. In recent years, the rate of caries has increased in many countries.
D. In recent years, the consumption of sugar has increased in many countries.