CBSE Class 10 Science Life Processes Assignment Set 06

This is Assignment Set 06 for CBSE Class 10 Science Chapter 5, Life Processes, with 22 mixed practice questions carrying 1, 3 and 5 marks, plus a short case based question. The questions test nutrition in plants and humans, the digestive enzymes, the heart and the nephron, and every answer is given step by step with the marks pattern shown in the section headings.

Very Short Answer Questions (1 Mark Each)

Question 1. Name the raw materials needed by green plants for photosynthesis?
Answer:
The raw materials are carbon dioxide and water. Sunlight and chlorophyll are the other requirements.
In simple words: Carbon dioxide and water are the raw materials.

Teacher's Note:
1. Name both raw materials.
2. Do not list sunlight as a raw material.

Question 2. What are the different modes of nutrition?
Answer:
There are two main modes of nutrition: autotrophic nutrition, in which the organism makes its own food, and heterotrophic nutrition, in which the organism depends on other organisms for food.
In simple words: Organisms either make their own food or get it from others.

Teacher's Note:
1. Give one example of each mode.
2. Green plants are autotrophs; animals are heterotrophs.

Question 3. Give the energy transformation that takes place in the process of photosynthesis?
Answer:
In photosynthesis, light (solar) energy is converted into chemical energy, which is stored in the glucose formed.
In simple words: Sunlight energy becomes food (chemical) energy.

Teacher's Note:
1. Write the energy before and after.
2. Chemical energy is stored in glucose.

Question 4. What are the types of heterotrophic nutrition?
Answer:
Heterotrophic nutrition is of three types: saprophytic (for example fungi such as bread mould), holozoic (for example amoeba and human beings) and parasitic (for example Cuscuta and tapeworm).
In simple words: Heterotrophs may feed on dead matter, take in solid food, or live on a host.

Teacher's Note:
1. Name the three types.
2. Add an example for each.

Question 5. State the form in which the following are stored:
(i) Unused carbohydrates in plants
(ii) The energy derived from food in humans
Answer:
(i) Unused carbohydrates are stored in plants in the form of starch.
(ii) The energy derived from food in humans is stored in the form of ATP (adenosine triphosphate).
In simple words: Plants store starch, and cells store energy as ATP.

Teacher's Note:
1. ATP is the energy currency of the cell.
2. Do not write glycogen for part (ii).

Question 6. State where are stomata ideally located? Are they cellular structures?
Answer:
Stomata are tiny pores that are found on the surface of leaves, generally more on the lower epidermis.
Yes, they are cellular structures. Each stoma is a pore surrounded by two guard cells, which open and close it.
In simple words: Stomata lie mostly on the underside of leaves and each pore has two guard cells.

Teacher's Note:
1. Name the lower epidermis.
2. Name the guard cells as the cells of the structure.

Question 7. Why are green plants called producers?
Answer:
Green plants prepare their own food from carbon dioxide and water by photosynthesis, using sunlight. This food is the source of energy for all other organisms, so green plants are called producers.
In simple words: Green plants make the food that all other organisms use.

Teacher's Note:
1. Link producers with photosynthesis.
2. Producers start every food chain.

Question 8. Which is more harmful urea or ammonia?
Answer:
Ammonia is more harmful. It is highly toxic, so in the liver it is changed into the much less toxic urea.
In simple words: Ammonia is more toxic than urea.

Teacher's Note:
1. Remember that the liver makes urea from ammonia.
2. Urea is less toxic.

Question 9. Which of the following contains less nitrogenous waste: the renal vein or the renal artery?
Answer:
The renal vein contains less nitrogenous waste, because the blood has been filtered in the kidney before it leaves through the renal vein. The renal artery brings the blood with wastes to the kidney.
In simple words: Blood leaving the kidney is cleaner than blood entering it.

Teacher's Note:
1. The renal artery enters the kidney with wastes.
2. The renal vein leaves with cleaned blood.

Question 10. What is the function of glomerulus?
Answer:
The glomerulus is a cluster of blood capillaries in the Bowman’s capsule. It filters the blood, so that nitrogenous waste and other small substances pass into the capsule.
In simple words: The glomerulus filters the blood in the nephron.

Teacher's Note:
1. Name the Bowman’s capsule.
2. Filtration is the first step of urine formation.

Short Answer Questions (2 to 3 Marks Each)

Question 11. Using only flowchart write the path of oxygen from nostrils to respiring tissue cell.
Answer:
Nostrils → Nasal cavity → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli → Blood capillaries around the alveoli → Haemoglobin of red blood cells (carried by blood through the heart and arteries) → Respiring tissue cell.
In simple words: Air passes down the air passages to the alveoli, and then blood carries oxygen to the cells.

Teacher's Note:
1. Follow the order of the air passage exactly.
2. End with haemoglobin and the cell.

Question 12. What criteria do we use to decide whether something is alive?
Answer:
We look for the following signs:
1. Movement and growth: living things grow and show movement. If there is no visible movement, there are still molecular movements.
2. Nutrition: they need food to get energy for their activities.
3. Respiration: they take in oxygen to break down food and release energy.
4. Excretion: they remove their waste products.
5. Reproduction: they produce new organisms like themselves.
In simple words: Living things grow, move, feed, breathe, excrete and reproduce.

Teacher's Note:
1. Give at least three criteria.
2. Molecular movement shows that even a still thing may be alive.

Question 13. Where do plants get each of the raw materials required for photosynthesis?
Answer:
Carbon dioxide: taken from the air through the stomata of the leaves. Aquatic plants use the carbon dioxide dissolved in water.
Water: absorbed from the soil by the roots (with minerals), and carried to the leaves by the xylem.
Sunlight: trapped by the chlorophyll in the chloroplasts of the green parts, mainly the leaves.
In simple words: Air gives carbon dioxide, soil gives water and the sun gives light.

Teacher's Note:
1. Give the source and the way of entry for each.
2. Mention the stomata and the roots.

Question 14. What are the adaptations of a leaf for photosynthesis?
Answer:
1. The leaf is broad and thin, which gives a large surface to absorb sunlight and a short path for gases.
2. Most chloroplasts are present in the cells (palisade cells) near the upper surface, where the light falls.
3. There are many stomata, mostly on the lower surface, for the exchange of carbon dioxide and oxygen.
4. Leaves are arranged so that they receive the maximum sunlight, and the veins (xylem and phloem) bring water and carry food.
In simple words: A leaf is flat, full of chloroplasts, and has stomata for gases.

Teacher's Note:
1. Give at least three adaptations.
2. Link each adaptation with its purpose.

Teacher's Note:
1. Make a table of type and function.
2. An adult has 32 teeth in all.

Teacher's Note:
1. Name the food each enzyme acts upon.
2. Two enzymes are enough.

Question 17. What is the function of digestive enzymes?
Answer:
Digestive enzymes are biological catalysts. They speed up the breakdown of large, insoluble food molecules into small, soluble molecules that can be absorbed into the blood.
For example, amylase changes starch into sugars, proteases such as pepsin and trypsin break proteins into peptides and amino acids, and lipase breaks fats into fatty acids and glycerol.
In simple words: Digestive enzymes break big food molecules into small ones that the body can absorb.

Teacher's Note:
1. Call enzymes biological catalysts.
2. Give one example for each food type.

Question 18. Briefly describe the shape and function of human white blood corpuscles.
Answer:
White blood corpuscles (WBCs) have no fixed shape; they are amoeboid and have a nucleus of varied shape. They do not contain haemoglobin.
Function: they protect the body from infection. They can squeeze out of the capillaries, surround and swallow germs, and they form antibodies. That is why they are called the soldiers of the body.
In simple words: WBCs are shapeless cells that fight germs.

Teacher's Note:
1. Mention amoeboid shape and the absence of haemoglobin.
2. Mention both swallowing germs and making antibodies.

Long Answer Questions (5 Marks Each)

Question 19. Explain the mechanism of photosynthesis.
Answer:
Photosynthesis is the process by which green plants make their food (glucose) from carbon dioxide and water, using sunlight and chlorophyll, and release oxygen. The chemical equation is: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ (in the presence of sunlight and chlorophyll).
The following events take place in the chloroplast:
1. Light phase: chlorophyll absorbs the light energy. The light energy is converted into chemical energy and water molecules are split into hydrogen and oxygen (photolysis). The oxygen is released.
2. Dark phase (needs no light): the hydrogen and the chemical energy are used to reduce carbon dioxide to carbohydrates (glucose).
The glucose is then changed into starch for storage.
In simple words: Chlorophyll traps light, water is split to release oxygen, and carbon dioxide is turned into glucose.

Teacher's Note:
1. Write the equation with the conditions.
2. Mention that oxygen comes from the splitting of water.

Question 20. Describe the alimentary canal of human beings.
Answer:
The alimentary canal is a long tube that starts with the mouth and ends at the anus.
1. Mouth: teeth chew the food, the tongue mixes it with saliva, and salivary amylase begins the digestion of starch.
2. Oesophagus: carries the food from the mouth to the stomach by peristalsis.
3. Stomach: a J-shaped muscular bag. Gastric glands make gastric juice, which has hydrochloric acid, pepsin and mucus. Pepsin digests proteins and the food becomes a semi-liquid chyme.
4. Small intestine: the longest part. It receives bile and pancreatic juice, makes intestinal juice and completes the digestion. Its inner wall has finger-like villi that absorb the digested food.
5. Large intestine: absorbs water from the undigested food. The semi-solid waste (faeces) is stored in the rectum and is passed out through the anus.
In simple words: Food moves from mouth to anus, digested step by step and absorbed in the small intestine.

Teacher's Note:
1. Describe each part in order with one function.
2. Name villi for absorption.

Question 21. Describe the structure and functioning of nephrons?
Answer:
The nephron is the structural and functional unit of the kidney. Each kidney has about a million nephrons.
Structure: (1) Bowman’s capsule, a thin-walled cup-shaped structure that contains a knot of blood capillaries called the glomerulus; (2) a long renal tubule, which has the proximal convoluted tubule, the loop of Henle and the distal convoluted tubule. The tubule opens into a collecting duct. A network of capillaries surrounds the tubule.
Working: (1) Ultrafiltration: blood is filtered in the glomerulus and the filtrate collects in Bowman’s capsule. (2) Selective reabsorption: useful substances like glucose, amino acids, salts and water are reabsorbed into the blood from the tubule. (3) Tubular secretion: some wastes are passed from the blood into the tubule. The remaining fluid is urine, which flows into the collecting duct.
In simple words: A nephron filters the blood, takes back the useful things and sends the waste out as urine.

Teacher's Note:
1. Do not call the nephron the unit of life; it is the unit of the kidney.
2. Write the three steps in order.

Question 22. Describe the internal structure of human heart.
Answer:
1. The human heart is four-chambered: two upper chambers, the right and left atria (auricles), and two lower chambers, the right and left ventricles. A wall called the septum separates the right and left sides. The heart is covered by the pericardium.
2. The right atrium receives deoxygenated blood from the body through the superior and inferior vena cava. A tricuspid valve guards the opening between it and the right ventricle.
3. The right ventricle pumps this blood through the pulmonary artery to the lungs.
4. The left atrium receives oxygenated blood from the lungs through the pulmonary veins. A bicuspid valve guards its opening to the left ventricle.
5. The left ventricle has the thickest wall. It pumps oxygenated blood into the aorta, which carries it to the whole body.
The valves allow the blood to flow in only one direction.
In simple words: The heart has four chambers, valves and a septum that keep oxygenated and deoxygenated blood apart.

Teacher's Note:
1. Name each chamber with the vessel that joins it.
2. The ventricles have thicker walls than the atria.

Case Based Question (3 Marks)

Question 23. The saliva contains an enzyme called salivary amylase that breaks down starch which is a complex molecule to give sugar. The food is mixed thoroughly with saliva and moved around the mouth while chewing by the muscular tongue. From the mouth, the food is taken to the stomach through the food-pipe or oesophagus. The stomach is a large organ which expands when food enters it. The muscular walls of the stomach help in mixing the food thoroughly with more digestive juices. These digestion functions are taken care of by the gastric glands present in the wall of the stomach. These release hydrochloric acid, a protein digesting enzyme called pepsin and mucus. The hydrochloric acid creates an acidic medium which facilitates the action of the enzyme pepsin. The mucus protects the inner lining of the stomach from the action of the acid under normal conditions.
(i) What is the name of the enzyme present in saliva?
(ii) What type of substance is secreted by gastric glands?
(iii) What is the role of mucus?
Answer:
(i) The enzyme in saliva is salivary amylase.
(ii) The gastric glands secrete gastric juice, which contains hydrochloric acid, the enzyme pepsin and mucus.
(iii) Mucus protects the inner lining of the stomach from the action of the hydrochloric acid.
In simple words: Saliva has amylase; gastric juice has acid, pepsin and mucus; mucus protects the stomach wall.

Teacher's Note:
1. Read the passage once and underline the key names.
2. Answer each part from the passage.