Eureka plus 7 science Solution/Answer key

LESSON: NUTRITION IN PLANTS - Eureka plus 7th science Solution
Exercises
I. 1. a saprophyte  2. autotrophic               3. chlorophyll     4. starch               5. photosynthesis            6. fix nitrogen
II. 1. X    2. X         3. ✓        4. X         5. X         6. X
III. 1. The process by which an organism obtains substances that provide energy, help in growth and maintain the body is called nutrition.
2. No. Birds are heterotrophs.
3. Living organisms that feed on other living organisms are known as heterotrophs.
4. Fungi are saprophytes.
5. Chloroplasts contain the green pigment called chlorophyll.
6. Yes. The leaves of plants such as crotons appear red because the green chlorophyll in such plants is masked by a red pigment.
7. Oxygen is produced during the process of photosynthesis.
8. Rhizobium bacteria live in the roots of plants such as beans, peas and grams.
9. Mistletoe is a 'Partial parasitic plant.
10. Food made by the leaves is transported to all parts of the plants through phloem tubes.
IV. 1. Autotrophs: Autotrophs are the organisms that make their own food by using simple substances from their surroundings. Examples: most plants, unicellular algae and some bacteria.
Heterotrophs: All organisms that obtain nutrition by feeding on other living organisms are called heterotrophic organisms. Examples: animals
2. Carbon dioxide + Water---  ---> Glucose (sugar) + Oxygen. 
3. Total parasitic plants : Plants that do not have  chlorophyll and obtain food and water from other plants are called total parasitic plants. For example, Cuscuta plant.
Partial parasitic plants  : They grow on trees such as mango and teak. They have chlorophyll and makes some of their food, but depend on the host plant for water and certain nutrients. For example, Mistletoe plant.
4. Growing a crop such as beans, after growing a crop such as wheat, in order to increase the fertility of the soil is called rotation of crops.
5. Some plants depend on other plants for food and water. Such plants are called parasitic plants. For example, Cuscuta.
6. Lichens are formed by the association of an alga and a fungus, and sometimes a photosynthesising bacterium. The organisms help each other to live.
VI 1. Leaves help a plant to make its food by a process called photosynthesis. During photosynthesis, light energy is converted into chemical energy. In this process, water and carbon dioxide combine to form sugar and oxygen.
2. The saprophyte (fungus) grows on organic matter. It secretes digestive juices which break down organic matter into simple substances and convert it into a solution. The saprophyte absorbs the solution and obtains nutrition.
3. The roots of bean plants contain certain bacteria called Rhizobium. These bacteria convert nitrogen gas from air into water-soluble nitrogenous substances, which are used by the plants to make proteins.
4. Parasitic plants depend on other living plants for food and water. A parasitic plant damages the host plant. Saprophytes are organisms that obtain nutrition from dead organic matter.
5. Boil some water in a container and place a leaf in it for about 3 minutes.
Remove the leaf from the boiling water and place it in a test tube and pour enough alcohol (ethanol or rectified spirit) to cover the leaf.
Place the test tube in boiling water and let the alcohol boil.
Stop boiling the alcohol when the leaf has turned completely colourless.
Wash the leaf with tap water. Lay the leaf on a clean dish and pour some dilute iodine solution on it.
A bluish colour will develop on the leaf. Iodine reacts with starch to give a bluish colour. This proves that starch is present in the leaves.
6. Chlorophyll is the green pigment present in the chloroplasts of leaves. They trap energy from sunlight and use it to make food for the plant. Some plants have leaves that do not appear green. These leaves also have chlorophyll. The chlorophyll in such leaves is masked by pigments of different colors.
Higher Order Thinking Skills
1. The leaf is exposed to sunlight.
2. The chlorophyll in the leaf cells absorbs the sunlight.
3. Air enters the stomata and carbon dioxide is taken into the leaf cells.
4. Energy-rich sugar molecules are formed.
5. Oxygen is formed and released through the stomata. 6. Excess sugar is converted to starch.
LESSON 2-NUTRITION  IN ANIMALS
I.  
1. small, Simple molecules                           2. Small intestine                              3.Amylase          
4. Fatty Acid                                                       5.Only Fats                                          6. Carbon dioxide, water, energy 
7. Cellular respiration                                     8. Amino acids
II. 1.e,   2.d         3.a          4.b,        5.c
III 1. Pancreatic juice       2. Blood                3. Amylase          4. Liver                  5. Glands in the inner walls of the stomach
6. Amino acids        7. Mucus              8. Pancreas
IV. 1, Digestion is the process through which the body converts useful substances in the food into simple substances. It takes place with the help of certain enzymes secreted by various organs of the digestive system.
2. Organs of the human digestive system are mouth, oesophagus, stomach, liver, pancreas, small intestine and large intestine.
3. Incisors are the four front teeth which are used to bite or cut food into smaller pieces. The canines are the tearing teeth present, one each on either side of the incisors, on each jaw.
4. Saliva is a digestive juice. It contains amylase that breaks down carbohydrates into sugar.
5. The inner walls of the small intestine have finger-like projections called villi. These villi are richly supplied with blood vessels. They increase the surface area for absorption of useful substances.
6. Complex fat molecules present in the food items such as butter, oil, milk and meat are broken into simple fatty acids in the small intestine.
V. 1. Food items such as wheat, potato and rice contain a carbohydrate called starch. A starch molecule is made up of several hundred glucose molecules linked together. It is a very large molecule and therefore the body cannot use it. The amylase secreted by the saliva in the mouth starts breaking down the carbohydrates. The pancreatic juice helps in further breaking down of carbohydrates into simple glucose molecules in the small intestine. The body uses glucose to obtain energy.
2. Proteins present in food items such as pulses, milk, meat and fish are complex substances. Each protein molecule is made up of many small amino acid molecules. The digestion of proteins starts in the stomach where the digestive juice called pepsin is present. The digestion of proteins is completed in the small intestine where the pancreatic juice breaks down proteins into amino acids. The body uses amino acids to grow and repair injured tissue.
3. The blood carries the glucose obtained from the digested food to every cell of the body. The glucose is broken down inside the cell in the presence of oxygen. During this process, the chemical energy present in the glucose is released along with carbon dioxide and water. This process is known as cellular respiration. This is how cells obtain energy and use it to perform different functions.
4. Ruminants have a four-chambered stomach. The first chamber is called the rumen. These herbivores eat quickly and store large amounts of grass in the rumen which contains millions of microbes and a large amount of saliva. The microbes begin to break down the food in the rumen. The animal now regurgitates the contents of the rumen back into the mouth several times to chew on it. The additional chewing helps in breaking down the cellulose contents further. From the rumen, the contents pass into the other two chambers before it reaches the fourth chamber. In these chambers, the hydrochloric acid and the gastric juices digest the proteins.
5. Amoeba lives in freshwater puddles and ponds and feeds mostly on remains of plants.
Nutrition in Amoeba involves the following:
• Ingestion: Amoeba senses a food particle, moves towards it and engulfs it.
Digestion: A food vacuole is formed around the engulfed food particle containing digestive juices, which break down the food particle into simple substances.
Assimilation: Amoeba uses these substances.
Egestion: The undigested portion is removed from the body.
Higher Order Thinking Skills
I. 1.The carbohydrate in the chapati is broken down into sugar by the saliva. Hence it tastes sweet when chewed for a long time.
2. Digestion is completed in small intestine, and the absorption of the nutrients by the blood vessels happens here. Therefore, smal intestine is richly supplied with blood vessels.
3. Vegetables and fruits contain a lot of fibre. This helps in moving the undigested food to the anus. Thus it cleans the digestive system. |
4. Mammals such as whales have teeth which help in biting and chewing their food. These animals are called fitter feeders as they have to strain their food from water.
II. 1.The moth feeds on nectar from flowers.
2. ‘No, the moth may collect nectar from different types of flowers.
3. The moth has a straw-like mouth part that helps in sucking nectar.
4. Bees and butterflies have similar straw-like mouth parts to suck nectar from flowers.
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