CBSE Class 10 Science Life Processes VBQs Set 08

This page has 16 value based and real life questions with answers for CBSE Class 10 Science Chapter 5, Life Processes, collected from question banks and competency based practice. The questions link the chapter to health and daily life, such as blood donation, dialysis and kidney transplant, smoking, tooth decay, blood pressure, cholesterol and exercise, and each answer is explained step by step.

Value Based Questions

Question 1. Rohan’s friend was seriously injured and lost a lot of blood. He was advised for blood transfusion immediately. But because of the rare blood group, it was not available. Immediately Rohan and his friends made efforts for the announcement to be made on TV and Radio. Soon they got many people to help them and a life was saved.
(a) What is the composition of blood?
(b) How is oxygen and carbon dioxide transported in our body?
(c) What values are being displayed by Rohan and his friends?
Answer:
(a) Blood has a fluid part, the plasma (about 55% of blood, mostly water with dissolved substances), in which the blood cells float: red blood cells (RBCs), white blood cells (WBCs) and platelets.
(b) Oxygen is carried mainly by haemoglobin, the pigment in red blood cells, from the lungs to the body cells. Carbon dioxide is more soluble in water than oxygen, so it is carried mostly in dissolved form in the plasma from the cells to the lungs.
(c) They showed helpfulness and concern for others, team work, social responsibility and good use of media (TV and radio) to serve society.
In simple words: Blood is plasma plus RBCs, WBCs and platelets; Rohan and his friends showed care and teamwork.

Teacher's Note:
1. Do not confuse the carriers: haemoglobin for oxygen, plasma for most of the carbon dioxide.
2. In the value part, name two or three values with the action that shows them.

Question 2. Ravi was diagnosed with kidney failure. He was advised to undergo dialysis for twice in a week. After undergoing dialysis for a month he was unable to continue the treatment as it is very painful. What alternative treatment solution can you suggest for Ravi other than dialysis.
Answer:
The alternative to dialysis is a kidney transplant.
In this surgery a healthy kidney from a donor is placed in the patient with kidney failure. One healthy kidney is enough to do the work of excretion, so a living person can donate one kidney.
It is a long-term solution, and the donor and patient must be matched by a doctor.
In simple words: A kidney transplant can replace painful, repeated dialysis.

Teacher's Note:
1. Name the transplant and say who can donate.
2. Mention that a person can live with one kidney.

Question 3. Smoking is the leading cause of lung cancer. Cigar smoke may contain even more toxic substances than cigarettes. Cigarette smoking can have major consequences on the lungs at all ages.
(i) What developmental defects can babies suffer if pregnant mothers smoke?
(ii) What is Smokers cough?
Answer:
(i) Babies whose mothers smoked during pregnancy may have lungs that develop abnormally, and they can also be born with low weight.
(ii) Smoke damages and paralyses the cilia, the tiny hairs in the air passage that sweep out dust and mucus. Mucus and dirt then collect, and the person coughs again and again to clear them. This is smoker’s cough. Smokers also get more colds and chest infections.
The value to learn: do not smoke and avoid being near smokers.
In simple words: Smoking harms the lungs of the smoker and the unborn baby, and causes a constant cough.

Teacher's Note:
1. Mention the cilia for part (ii).
2. Add one health message at the end.

Question 4. If the teeth are not cleaned regularly, they become covered with a sticky yellowish layer W of food particles and bacteria. Since layer W covers the teeth the alkaline liquid X secreted by glands Y inside the mouth cannot reach the teeth surface to neutralize the acid formed by the action of organisms Z on sugary food and hence tooth decay sets in.
(i) What is W known as?
(ii) What is X and Y?
(iii) What are organisms Z?
(iv) State one way of removing layer W from the teeth.
Answer:
(i) W is dental plaque.
(ii) X is saliva and Y is the salivary glands.
(iii) Z are bacteria, which act on sugary food to produce acid.
(iv) Plaque can be removed by brushing the teeth properly twice a day (and rinsing the mouth after meals).
In simple words: Unbrushed teeth collect plaque, bacteria make acid under it and the teeth decay.

Teacher's Note:
1. Link plaque, acid and decay in a chain.
2. Saliva is slightly alkaline and cannot reach the tooth under plaque.

Question 5. Tooth enamel is the hardest substance in our body. Name the compound of which it is made up of. At what pH of the mouth it gets corroded? State the role of bacteria present in the mouth. Suggest a method to prevent tooth decay.
Answer:
Enamel is made of calcium phosphate (calcium hydroxyapatite).
It gets corroded when the pH of the mouth falls below 5.5.
Bacteria in the mouth act on sugar and food particles left on the teeth and produce acids. The acid lowers the pH and corrodes the enamel, which forms cavities.
Tooth decay can be prevented by brushing after meals, rinsing the mouth and avoiding sticky sugary food.
In simple words: Acid made by mouth bacteria dissolves the calcium phosphate of enamel, so clean your teeth.

Teacher's Note:
1. Remember pH 5.5 as the limit.
2. Name one habit that prevents decay.

Question 6. Which organs can be donated by a brain-dead patient?
Answer:
After a person is declared brain-dead, the heart may keep beating with machine support, so the organs stay healthy for transplant.
The organs that can be donated include the kidneys, liver, heart, lungs, pancreas and intestine. Tissues such as the corneas, skin, bones and heart valves can also be donated.
One donor can save several lives, so organ donation is a great social service done with the consent of the family.
In simple words: A single brain-dead donor can give many organs and save many lives.

Teacher's Note:
1. Name at least four organs.
2. Mention the value of organ donation.

Real Life and Health Questions

Teacher's Note:
1. Write systolic over diastolic as 120/80.
2. In the table, the third category is high normal, not high.

Teacher's Note:
1. Compare each value with the chart row by row.
2. Name both missing columns.

Question 9. Amount of urine produced generally decreases in summers as compared to other seasons if we don’t keep ourselves sufficiently hydrated. Justify.
Answer:
The amount of urine depends on how much excess water and dissolved waste is present in the body. It is controlled by selective reabsorption in the renal tubule of the nephron.
In summer we lose more water as sweat. To maintain the water balance, the kidneys reabsorb more water back into the blood, so a small amount of concentrated urine is formed.
So we should drink enough water in summer.
In simple words: In summer the body saves water, so less urine is made unless we drink enough.

Teacher's Note:
1. Link sweating with greater reabsorption.
2. End with the health message to stay hydrated.

Question 10. Justify Plants biological wastes are sometimes riches for humans.
Answer:
Plants store many waste products in leaves, bark and special tissues, and several of these are very useful to humans.
Examples: latex of the rubber tree gives natural rubber; resin of pine gives turpentine; gums are used as adhesives; tannins are used in tanning and in tea; essential oils of eucalyptus, jasmine and orange are used in perfumes and medicines; and the bark of cinchona gives the medicine quinine.
So the wastes of plants are valuable products for humans.
In simple words: Plant wastes such as latex, resin, gum and oils are useful to us.

Teacher's Note:
1. Give at least two named examples.
2. Say what each is used for.

Question 11. The breakdown of complex substances into simpler substances by action of enzymes released by anaerobic bacteria is called fermentation. By this method we can prepare only ethanol. In this, firstly, sugarcane juice and water are mixed and heated to form sweet liquid called molasses. Then, it breaks into glucose and fructose and then further, glucose and fructose break into further simpler substances. This method is generally carried out in breweries.
(i) Name the enzyme that converts sugarcane juice into glucose and fructose.
(ii) Which enzyme is responsible for conversion of glucose and fructose into ethanol and carbon dioxide?
(iii) What is the condition for fermentation?
Answer:
(i) The enzyme invertase changes cane sugar into glucose and fructose.
(ii) The enzyme zymase (from yeast) converts glucose and fructose into ethanol and carbon dioxide.
(iii) Fermentation takes place in the absence of oxygen (anaerobic conditions).
Glucose and fructose are therefore intermediate substances and not the final products. The final products are ethanol and carbon dioxide.
In simple words: Yeast enzymes turn sugar into alcohol and carbon dioxide without oxygen.

Teacher's Note:
1. Name both enzymes and their jobs.
2. Remember that fermentation is anaerobic respiration.

Question 12. Why does lack of oxygen in muscles often lead to cramps among cricketers?
Answer:
During running and other hard activity, the muscles need a lot of energy quickly, and the oxygen supply is not enough.
Without oxygen, the pyruvate formed from glucose in the cytoplasm is converted into lactic acid, with the release of a little energy: glucose → pyruvate → lactic acid + energy.
Lactic acid collects in the muscle cells and causes cramps.
In simple words: No oxygen means lactic acid builds up in the muscles, and that gives cramps.

Teacher's Note:
1. Name lactic acid as the cause.
2. This is anaerobic respiration in muscle.

Question 13. Why does the breathing rate increase during vigorous exercise?
Answer:
During vigorous exercise the body muscles need more energy.
More energy is obtained by respiration, which needs more oxygen and also produces more carbon dioxide.
So the breathing rate increases to take in more oxygen and to remove the extra carbon dioxide.
In simple words: Hard exercise needs more oxygen, so we breathe faster.

Teacher's Note:
1. Link energy with oxygen demand.
2. Add the removal of carbon dioxide.

Question 14. Haemodialysis is a common type of dialysis. It removes waste products from the blood such as excess salts, and urea which are insufficiently removed by the kidney in patients with kidney failure. During the procedure, the patient’s blood is cleaned by filtration through a series of semipermeable membranes before being returned to the body of the patient. On the basis of this, answer the following questions:
(A) (i) Name the filtering units present in the human kidneys.
(ii) Name the main excreting waste removed by kidneys from blood.
(B) What are the two main functions of kidneys?
(C) What are the major factors on which the amount of water reabsorbed in the part of nephron depends?
Answer:
(A)(i) The filtering units of the kidneys are the nephrons.
(ii) The main waste removed from the blood is urea.
(B) The two main functions of the kidneys are excretion (removing nitrogenous waste such as urea from the blood) and osmoregulation (keeping the salt and water balance of the body).
(C) The amount of water reabsorbed depends on (1) how much excess water is present in the body and (2) how much dissolved waste has to be excreted.
In simple words: Haemodialysis does the cleaning job of failed kidneys.

Teacher's Note:
1. Name nephron, urea, excretion and osmoregulation.
2. Give two factors in part (C).

Case Based Questions

Question 15. Jeet’s mother often complains about indigestion and hyperacidity in the stomach and she takes antacid to get relief from the pain.
(A) (i) Over production of which substance is the probable reason for such complaint?
(ii) Why is the production of this substance necessary?
(B) (i) Does this substance serve any other function for the stomach?
(ii) How does the stomach prevent itself from the harmful effects of over production of this substance?
(C) (i) How does the stomach regulates the flow of partially digested food?
(ii) Which part of the alimentary canal receives the food from the small intestine?
Answer:
(A)(i) Too much hydrochloric acid (HCl) in the gastric juice.
(ii) HCl makes the medium in the stomach acidic, so that the enzyme pepsin can digest proteins.
(B)(i) Yes, it also kills the germs that enter the stomach with food.
(ii) The stomach wall releases mucus, which coats the inner lining and protects it from the acid.
(C)(i) The exit of the stomach is guarded by a sphincter muscle, which opens from time to time and lets the food go into the small intestine in small amounts.
(ii) The food from the small intestine passes into the large intestine.
An antacid is a mild base that neutralises the extra acid, but a person with repeated acidity should see a doctor.
In simple words: Excess stomach acid causes acidity; mucus protects the stomach and an antacid neutralises the acid.

Teacher's Note:
1. Remember all three uses of mucus and HCl.
2. Do not forget the sphincter for part (C).

Question 16. In 2015, one of the popular noodles brands was banned in India since it was concluded to be unhealthy to eat. Though the ban was removed after some time, it triggered debates which continue till date in some groups of people. Who decides if a packed food product can be sold in the market or not? In India, the Food Safety and Standards Authority of India (also known as FSSAI) is responsible for protecting people’s health by supervising the quality of food. FSSAI regulates the quality of packed food products by issuing rules and guidelines which each manufacturer needs to comply with. For example, as per the FSSAI rules, each packed food item must have a green dot or red dot to indicate whether it is a veg or non-veg product. Another regulation ensures that packed food items have labels showing the nutritional value of the food product including the information on how much energy can one derive from that food product. The food’s energy value is measured in this unit called calorie. If a food packet says that 100 g of that food would give us 400 calories, does our body get the full 400 calories or less than that? Note that some energy is spent in digesting the food as well. Digestion is essential for extracting the energy from the food.
(A) In which organ (if any) of the digestive system does the food get converted to usable energy? How is the energy transferred from that part to the rest of the body?
(B) There are various muscles present in the human digestive system known as sphincters. Two examples of those are given below: (i) Pyloric sphincter - At the junction of stomach and small intestine (ii) Anal sphincter - At the anus. Give ONE most likely consequence of malfunctioning of each of these sphincters.
(C) The average pH of the mouth is 6.5 to 7.5, oesophagus 7, stomach 1 to 2, liver 7 to 7.5, pancreas 8 to 8.3, small intestine 6.5 to 7 and large intestine 5.5 to 7.
(i) Stomach secretes acidic juices with pH having 1 to 2 but lining of the stomach rarely gets corroded. Explain.
(ii) The pH of the pancreas is 8 to 8.3, it means pancreas secretes alkaline juices in the small intestine. How is the alkaline nature of pancreatic juices helpful in the digestion of food?
Answer:
(A) No organ of the digestive system converts food into usable energy. The digestive system only breaks the food into simple soluble substances such as glucose, amino acids, and fatty acids, which are absorbed in the small intestine into the blood. The blood carries them to every cell, where respiration releases the energy. So the body does not get the full calorie value, since some energy is spent in digestion.
(B)(i) If the pyloric sphincter does not work properly, food may pass into the small intestine too fast, causing poor digestion and absorption.
(ii) If the anal sphincter does not work properly, the person cannot hold back faeces (faecal incontinence).
(C)(i) The gastric glands also release mucus, which forms a protective layer on the inner lining of the stomach and protects it from the acid.
(ii) The food coming from the stomach is acidic. The alkaline pancreatic juice neutralises the acid and makes the medium alkaline, which is needed for the pancreatic enzymes to act on the food.
In simple words: Digestion only prepares nutrients; cells release the energy. Mucus protects the stomach and pancreatic juice neutralises the acid.

Teacher's Note:
1. Digestion makes nutrients; respiration makes energy.
2. Use the pH values in the table as evidence in part (C).