Tuesday, April 26, 2011
Sunday, April 24, 2011
Chapter 1 - Nutrition in Plants
Why do organisms need to take food?
All living organisms require food to survive. It gives them energy to perform various activities. All activities such as playing, running, walking, studying, etc. require energy. The various components present in our food such as carbohydrates, proteins, fats, vitamins, and minerals provide energy to our body. These are also important for growth and development of the body.
Distinguish between a parasite and a saprotroph.
| Parasite | Saprotroph |
| The organism that grows on the body of another organism and derives nutrients from it is known as a parasite. | The organism that obtains nutrients from the dead or decaying organic matter is called saprotroph. |
| Examples of parasites are Cuscuta and orchids. | Examples of saprotrophs are fungi and some bacteria. |
How would you test the presence of starch in leaves?
Experiment to test the presence of starch in leaves:
Take two healthy green potted plants of the same type. Keep one potted plant in a dark room for one or two days in order to remove all the starch from the leaves. Keep the other plant in sunlight. Now, take one leaf from each potted plant and put a few drops of iodine solution on them. Then note down the observation.
Plants kept in light and dark conditions
No blue black colour will be observed on the leaves of the plant kept in the dark room. This indicates the absence of starch. Blue black colour will be observed on the leaves of the plant kept in sunlight. This indicates the presence of starch.
Give a brief description of the process of synthesis of food in green plants.
Photosynthesis is defined as the process in which the chlorophyll-containing plant cells synthesise food in the form of carbohydrates, using carbon dioxide and water in the presence of solar energy.
Photosynthesis
Sources of raw materials required for photosynthesis:
(a) Water is taken in from the roots of the plant and is transported to the leaves.
(b) Carbon dioxide from the air enters the leaves through the tiny pores called stomata and diffuses to the cells containing chlorophyll.
(c) Solar energy is used to break water into hydrogen and oxygen. This hydrogen is combined with carbon dioxide to form food for the plants, which is ultimately used by the animals as well.
Thus, photosynthesis can be represented by the following equation.
Show with the help of a sketch that the plants are the ultimate source of food.
Photosynthesis
Fill in the blanks:
(a) Green plants are called __________ since they synthesise their own food.
(b) The food synthesised by the plants is stored as __________.
(c) In photosynthesis solar energy is captured by the pigment called ___________.
(d) During photosynthesis plants take in ___________and release ___________.
(a) Green plants are called __autotrophs__ since they synthesise their own food.
(b) The food synthesised by the plants is stored as __starch__.
(c) In photosynthesis solar energy is captured by the pigment called chlorophyll__.
(d) During photosynthesis plants take in __carbon dioxide__ and release __oxygen__.
Name the following:
(i) A parasitic plant with yellow, slender and tubular stem.
(ii) A plant that has both autotrophic and heterotrophic mode of nutrition.
(iii) The pores through which leaves exchange gases.
(i) Cuscuta
(ii) Pitcher plant
(iii) Stomata
Tick the correct answer:
(a)Amarbel is an example of
(i) autotroph
(ii) parasite
(iii) saprotroph
(iv) host
(b)The plant which traps and feeds on insects is
(i) Cuscuta
(ii) china rose
(iii) pitcher plant
(iv) rose
(a)Amarbel is an example of
(i) autotroph
(ii) parasite
(iii) saprotroph
(iv) host
(b)The plant which traps and feeds on insects is
(i) Cuscuta
(ii) China rose
(iii) pitcher plant
(iv) rose
Match the items given in Column I with those in Column II:
| Column I | Column II |
| Chlorophyll | Bacteria |
| Nitrogen | Heterotrophs |
| Amarbel | Pitcher plant |
| Animals | Leaf |
| Insects | Parasite |
| Column I | Column II |
| Chlorophyll | Leaf |
| Nitrogen | Bacteria |
| Amarbel | Parasite |
| Animals | Heterotrophs |
| Insects | Pitcher plant |
Mark ‘T’ if the statement is true and ‘F’ if it is false:
(i) Carbon dioxide is released during photosynthesis. (T/F)
(ii) Plants which synthesise their food themselves are called saprotrophs. (T/F)
(iii) The product of photosynthesis is not a protein. (T/F)
(iv) Solar energy is converted into chemical energy during photosynthesis. (T/F)
(i) Carbon dioxide is released during photosynthesis. (F)
(ii) Plants which synthesise their food themselves are called saprotrophs. (F)
(iii) The product of photosynthesis is not a protein. (T)
(iv) Solar energy is converted into chemical energy during photosynthesis. (T)
Wednesday, April 6, 2011
Chapter 2 - Nutrition in Animals
Fill in the blanks:
(a) The main steps of nutrition in humans are __________, __________, ___________, __________ and __________
(b) The largest gland in the human body is __________.
(c) The stomach releases hydrochloric acid and ________ juices which act on food.
(d) The inner wall of the small intestine has many finger-like outgrowths called __________.
(e) Amoeba digests its food in the __________.
(a) The main steps of nutrition in humans are __ingestion__, __digestion__, __absorption__, __assimilation__ and __egestion__.
(b) The largest gland in the human body is __liver__.
(c) The stomach releases hydrochloric acid and __digestive__ juices which act on food.
(d) The inner wall of the small intestine has many finger-like outgrowths called __villi__.
(e) Amoeba digests its food in the _food vacuole_.
Mark ‘T’ if the statement is true and ‘F’ if it is false:
(a) Digestion of starch starts in the stomach. (T/F)
(b) The tongue helps in mixing food with saliva. (T/F)
(c) The gall bladder temporarily stores bile. (T/F)
(d) The ruminants bring back swallowed grass into their mouth and chew it for some time. (T/F)
(a) Digestion of starch starts in the stomach. (F)
(b) The tongue helps in mixing food with saliva. (T)
(c) The gall bladder temporarily stores bile. (T)
(d) The ruminants bring back swallowed grass into their mouth and chew it for some time. (T)
Tick ( √) mark the correct answer in each of the following:
(a) Fat is completely digested in the
(i) stomach
(ii) mouth
(iii) small intestine
(iv) large intestine
(b) Water from the undigested food is absorbed mainly in the
(i) stomach
(ii) food pipe
(iii) small intestine
(iv) large intestine
(a) Fat is completely digested in the
(i) stomach
(ii) mouth
(iii) small intestine √
(iv) large intestine
(b) Water from the undigested food is absorbed mainly in the
(i) stomach
(ii) food pipe
(iii) small intestine
(iv) large intestine √
Question 4:
Match the items of Column I with those given in Column II:
| Column I | Column II |
| Food components | Product(s) of digestion |
| Carbohydrates | Fatty acids and glycerol |
| Proteins | Sugar |
| Fats | Amino acids |
| Column I | Column II |
| Food components | Product(s) of digestion |
| Carbohydrates | Sugar |
| Proteins | Amino acids |
| Fats | Fatty acids and glycerol |
Question 5:
What are villi? What is their location and function?
Villi are tiny finger-like projections originating from the walls of the small intestine. They increase the surface area for absorption of the digested food. The blood vessels present inside the villi can absorb the nutrients from the digested food.
Structure of a villus
Question 6:
Where is the bile produced? Which component of the food does it help to digest?
Liversecretes the bile juice which is stored in the gall bladder. Bile plays an important role in the digestion of fats.
Question 7:
Name the type of carbohydrate that can be digested by ruminants but not by humans. Give the reason also.
Cellulose is a type of carbohydrate that can be digested by ruminants and not by humans. Ruminants have a large sac-like structure between small and large intestine where the food containing cellulose is digested by the action of certain bacteria. On the other hand, humans cannot digest cellulose, as the cellulose digesting enzymes are absent in them.
Question 8:
Why do we get instant energy from glucose?
Glucose is a simple sugar. Carbohydrates, when consumed, have to be digested into glucose. As glucose can be easily absorbed in blood, it provides energy to the body. Hence, when glucose is directly taken, it does not have to be digested and thus acts as an instant source of energy.
Question 9:
Which part of the digestive canal is involved in:
(i) absorption of food ____.
(ii) chewing of food ____.
(iii) killing of bacteria ____.
(iv) complete digestion of food ____.
(v) formation of faeces ____.
(i) absorption of food __small intestine__
(ii) chewing of food __buccal cavity__
(iii) killing of bacteria __stomach__
(iv) complete digestion of food __small intestine__
(v) formation of faeces __large intestine__
Question 10:
Write one similarity and one difference between the nutrition in Amoeba and human beings.
Similarity between nutrition in Amoeba and human beings:
Both Amoeba and humans require energy for the growth and maintenance of their bodies. This energy is derived from the food that they eat. The food that they consume is always in a complex form and is therefore broken down into simpler forms by the process of digestion. Hence, both these organisms are heterotrophs.
Differences between nutrition in Amoeba and human beings:
| | Digestion in Humans | | Digestion in Amoeba |
| (i) | Humans have a mouth and a complex digestive system. | (i) | Mouth and digestive system are absent in Amoeba. |
| (ii) | Digestive juices are secreted in the buccal cavity, stomach, and small intestine. | (ii) | Digestive juices are secreted in the food vacuole. |
| (iii) | Digestion of carbohydrates, proteins, and fats starts in separate regions. | (iii) | All the food components are digested in the food vacuole. |
Question 11:
Match the items of Column I with suitable items in Column II
| - | Column I | - | Column II |
| (a) | Salivary gland | (i) | Bile juice secretion |
| (b) | Stomach | (ii) | Storage of undigested food |
| (c) | Liver | (iii) | Saliva secretion |
| (d) | Rectum | (iv) | Acid release |
| (e) | Small intestine | (v) | Digestion is completed |
| (f) | Large intestine | (vi) | Absorption of water |
| - | - | (vii) | Release of faeces |
| - | Column I | - | Column II |
| (a) | Salivary gland | (iii) | Saliva secretion |
| (b) | Stomach | (iv) | Acid release |
| (c) | Liver | (i) | Bile juice secretion |
| (d) | Rectum | (ii) | Storage of undigested food |
| (e) | Small intestine | (v) | Digestion is completed |
| (f) | Large intestine | (vi) | Absorption of water |
Question 12:
Label the following figure of the digestive system.
A part of human digestive system
Question 13:
Can we survive only on raw, leafy vegetables/grass? Discuss.
No.Humans cannot survive only on raw, leafy vegetables, or grass. It is because the grass is rich in cellulose, which is a type of carbohydrate that humans are not able to digest due to the absence of cellulose-digesting enzymes.
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