Life Processes: 10 CBSE Science Biology

Question:

1. What is the role of mucus in stomach?
2. How exit of food from the stomach is regulated?
3. Where does food enter from stomach?

Answer:

1. Mucus protects the inner lining of the stomach from the action of the acid under normal conditions.
2. The exit of food from the stomach is regulated by sphincter muscles which release it small amounts into the small intestine.
3. From stomach, food enters into the small intestine.

Question:

1. What is the nature of food coming from stomach?
2. Mention any two structural modifications in small intestine which help in absorption of food.

Answer:

1. The food coming from stomach is acidic in nature.
2. (i) The inner lining of the small intestine has numerous finger-like projections called as villi which increase the surface area for absorption.
   (ii) Small intestine is a long coiled tube due to which digested food stay longer and absorbed as much as possible.

Question:

1. Name the extensively coiled structure of alimentary canal.
2. Compare length of small intestine in herbivores and carnivores.

Answer:

1. Small intestine.
2. The length of the small intestine differs in various animals depending on the food they eat. Herbivores, eating grass need a longer small intestine to allow the cellulose to be digested whereas carnivores have a shorter small intestine because meat is comparatively easy to digest.

Question: Represent the equation of photosynthesis. Explain the steps involved in photosynthesis. In which way are the steps involved in photosynthesis. In which way are the steps of photosynthesis different in desert plants?

Answer:

Three events that occur during photosynthesis are:

1. Absorption of light energy by chlorophyll.
2. Conversion of light energy into chemical energy and splitting of water into hydrogen and oxygen.
3. Reduction of CO₂ into carbohydrates.

Desert plants take up CO₂ at night and prepare an intermediate molecule. The intermediate molecule is acted upon by the energy absorbed by the chlorophyll during the day to make carbohydrates.

Question:

1. A product is formed in our muscles due to breakdown of glucose when there is a lack of oxygen. Name the product and also mention the effect of build up of this product.
2. Differentiate between fermentation in yeast and aerobic respiration on the basis of end products formed.

Answer:

1. lactic acid is formed. Formation of lactic acid in the muscles cramps.
2. During fermentation in yeast, ethanol is formed while in aerobic respiration, carbon dioxide and water are formed. The energy (ATP) released in the process of fermentation is also very less as compared to the aerobic respiration.

Question: During the respiration of an organism ‘A’ one molecule of glucose produces two ATP molecules whereas in the respiration of another organism ‘B’, one molecule of glucose produces 38 ATP molecules.

1. Which organism is undergoing aerobic respiration?
2. Which organism is undergoing anaerobic respiration?
3. Which type of organism A or B can convert glucose into alcohol?
4. Name one organism which behaves like A.
5. Name two organism which behave like B.

Answer:

1. Organism ‘B’
2. Organism ‘A’
3. Organism ‘A’
4. Yeast
5. Human being

Question:

1. What happens to the heart when muscles work harder?
2. Which body system is directly affected when a person has heart disease?
3. Which cells increase in number during infection?

Answer:

1. When muscles work harder, they need more oxygen . So, heart begins to pump blood faster to overcome that need.
2. Circulatory system is directly affected when a person has heart disease.
3. Number of white blood corpuscles (WBC’s) increases during infection.

Question: What will happen if:

1. Peristaltic movements do not occur all along the oesophagus?
2. There is no platelets in blood?
3. Rings of cartilage are not present in the trachea?

Answer:

1. If peristaltic movements do not occur, the food will not be able to be pushed forward, into the stomach.
2. In case of no platelets, blood will not clot during bleeding.
3. In absence of rings of cartilage, air passage will collapse.

Question: What is lymph? How is composition of lymph different from blood plasma? What is the direction of its flow? List two functions of lymphatic system.

Answer: Lymph is a circulatory fluid which flows in the lymphatic capillaries which join to form large lymph vessels.

Composition of Lymph: Lymph is colorless and contains less protein than plasma.
Lymph flow from tissues to the heart.

Functions:
(i) Lymph carries digested and absorbed fat from intestine.
(ii) It drains excess fluid from extra-cellular space back into blood.

Question: What is ‘translocation’ ? Why is it essential for plants? Where in plants are the following synthesized:
(i) Sugars (ii) Hormones

Answer: Translocation: Transport of food prepared in the leaves to the other parts of the plants is known as translocation.

Translocation is essential for the plants for the supply of food to all parts of the plants. As food is needed for producing energy during its oxidation. Energy is then needed by all parts of the plants to perform their activities.

(i) Sugars are synthesized in the leaves and than transported to storage organs of roots, fruits and seeds.

(ii) Hormones are synthesized at the tip of the stem and at the tip of the roots.

Question: Name the glands associated with digestion of starch in human digestive tract and mention their role. How is required pH maintained in the stomach and small intestine?

Answer:

1. Salivary glands: salivary amylase break starch into sugar.
2. Pancreas: pancreatic amylase (juice) digest starch.
3. Intestinal glands: intestinal amylase – digest starch.
4. Acidic pH in stomach: due to Hydrochloric acid secreted by stomach.
5. Alkaline pH in small intestine:due to bile (liver) / pancreatic juice (pancreas).