CBSE Class 10 Biology Revision Worksheet Set C

VALUE BASED QUESTIONS

Question. Ahmad is a 50 year old man who is mainly a sedentary worker. He always gets his medical check up done once in a year. Till last year all his blood reports were normal. This year his blood (and even urine) tests showed the presence of large quantities of sugar. The doctor gave him some medicines to control sugar. The doctor also asked him to avoid certain food items and adopt a healthy life-style.
(a) Name the disease which Ahmad is suffering from.
(b) Name the gland whose malfunctioning causes this disease.
(c) How does the malfunctioning of this gland cause this disease ?
(d) What is done if this disease does not get controlled by taking oral medicines ?
(e) Name one vital organ which gets damaged if this disease persists uncontrolled for a long time.
(f) What life-style changes would you suggest for Ahmad which can help him control this ‘disease’ ?
Answer : (a) Ahmad is suffering from ‘diabetes’.
(b) Malfunctioning of pancreas causes diabetes.
(c) Pancreas makes and secretes insulin hormone into the blood. The function of insulin hormone is to lower the blood sugar level (or blood glucose level). If due to malfunctioning, pancreas does not produce and secrete sufficient amount of insulin hormone into blood, then the sugar level in blood rises too much leading to diabetes.
(d) The persons having severe diabetes which cannot be controlled by medicines are given insulin injections.
(e) If uncontrolled diabetes persists for a long time, it may damage kidneys.
(f) Ahmad can control diabetes :
(i) by controlling diet (by avoiding sweet food items containing sugar such as chocolates, sweets, soft drinks, etc.),
(ii) by taking regular physical exercise (including brisk walk, etc.), and
(iii) by reducing weight.

Question. Dodi is the only child of his rich parents. He insisted on getting a new motorbike on his 16th birthday. Though Dodi was underage by two years for obtaining a driving licence but he started driving motorbike without a driving licence. He even did not wear any protective equipment while driving the motorbike. Neighbours usually saw Dodi driving the motorbike very fast and rashly. He did not obey any traffic rules while driving. One day Dodi was driving his motorbike very fast on the main road with a friend seated behind him. He was trying to show off his misplaced sense of adventure by performing some dangerous stunts. Just then a heavily loaded truck appeared on the road in front of him. When this truck applied brakes suddenly to save a dog crossing the road, Dodi could not stop his speeding motorbike in time. The motorbike went under the truck banging Dodi’s head against the rear side of truck. Dodi was hurt badly. Dodi was rushed to the nearby hospital where he was declared brought dead. Dodi’s friend was lucky to escape with minor injuries.
The
(a) What type of injury do you think Dodi could have received that led to his immediate death ?
(b) Which protective equipment Dodi was not wearing at the time of the accident ?
(c) Which body part/vital organ of Dodi could have been protected by wearing the above protective equipment that could have perhaps saved Dodi’s life ?
(d) Do you think it is good to perform stunts on a running motorbike ? Give two reasons for your answer.
(e) What advice would you give to young children to avoid such unfortunate incidents ?
(f) What advice would you give to the parents of such children ?
Answer : (a) Dodi must have received a serious head injury.
(b) Dodi was not wearing a helmet at the time of accident.
(c) Wearing helmet could have protected the head of Dodi during the accident. It could have prevented or minimised the head injury. Helmet also protects the vital organ ‘brain’ which is inside the skull.
(d) No, it is not. Performing stunts on running motorbikes endanger the life of biker himself as well as that of other road users. Performing stunts on motorbike is like attempting to commit suicide.
(e) The children should drive motorbikes (and other vehicles like cars, etc.) on attaining the age of 18 years after learning all the traffic rules and obtaining a proper driving licence. They must wear helmet while driving motorbike and obey traffic rules. They must not attempt any risky stunts and keep the speed under control. Remember : speed thrills but kills.
(f) The parents should not gift (or lend) vehicles like motorbikes and cars to their underage children out of misplaced sense of love and affection or to show off their riches to the society. Those parents who do such things are actually the biggest enemies of their own children.

Question. Seeta and Geeta are neighbours in the same colony where they live. Seeta’s father and Geeta’s father both work in the same company and earn equal salary (or equal money). Seeta has one brother whereas Geeta has four brothers and sisters. Geeta is very bright in her studies. Earlier Geeta used to study in one of the top city schools alongwith Seeta but now her father has shifted Geeta to an ordinary school. Seeta’s family has a new car whereas Geeta’s family has an old scooter. Seeta and her brother wear beautiful clothes whereas Geeta’s siblings wear ordinary clothes. Seeta’s mother is very healthy whereas Geeta’s mother usually suffers from one ailment or another. Seeta’s home atmosphere is relaxed and happy whereas there is always some tension in Geeta’s house.
(a) What do you think is the main reason for the lower living standard of Geeta’s family than Seeta’s family (though their incomes are equal) ?
(b) What is the most probable reason for shifting Geeta from one of the top schools to an ordinary school (though she is very bright in studies) ?
(c) What type of measures do you think were not taken by Geeta’s parents at appropriate times in the past for limiting the size of their family ?
(d) What factor is responsible for the poor health of Geeta’s mother (whereas Seeta’s mother is very healthy) ?
(e) What values are displayed by Seeta’s parents in this episode ?
Answer : (a) The main reason for the comparatively lower living standard of Geeta’s family is their large family consisting of 7 persons (father, mother and 5 children) whereas Seeta’s family has only 4 persons (father, mother and 2 children). Due to this, in Geeta’s family, the father’s income is used for the upkeep of 7 persons whereas in Seeta’s family, an equal income is available for just 4 persons.
(b) The most probable reason for shifting Geeta from a top school to an ordinary school is that due to large number of children, her father cannot afford much higher school fee in a top school.
(c) Geeta’s parents did not take family planning measures (or birth control measures) to control the size of their family by having less number of children at the appropriate times in the past.
(d) Every pregnancy puts a lot of demands (nutritional, physical and emotional) on the body of the mother.
So, the frequent pregnancies (to have a large number of children) have spoiled the health of Geeta’s mother. On the other hand, just two pregnancies (to have only two children) have kept Seeta’s mother in good health.
(e) Seeta’s parents displayed the values of (i) Awareness of birth control measures (to limit the size of their family) (ii) Concern for the health of mother of children (iii) Desire to provide best possible education and facilities to children, and (iv) National responsibility (of not adding too much to country’s population).

Question. Mamta is a married woman having two children. She does not want to have any more children. Her husband also supports her decision not to have more children. They are both happy with just two children, both of whom are daughters.
(a) Suggest any two types of birth control methods which Mamta and her husband can make use of to avoid pregnancy. Explain how these methods work to prevent pregnancy.
(b) Which birth control method has additional advantage of giving protection from sexually transmitted diseases (STDs) ?
(c) What values are displayed by Mamta and her husband in not wanting to have any more children ?
Answer : (a) The two common type of birth control methods which can be followed by Mamta and her husband are : (i) Barrier Methods. In these methods, a condom (nirodh) is used by the husband or a diaphragm (cap) is used by the wife to prevent the meeting of sperms with ovum (or egg) and prevent pregnancy.
(ii) Chemical Methods. In these methods, oral pills and vaginal pills can be used by the wife. Oral pills contain hormones which stop ovaries from releasing the ovum (or egg) into oviduct. Vaginal pills contain the chemicals called spermicides which kill the sperms.
(b) The use of condom (nirodh) is a birth control method which provides additional advantage of protection from sexually transmitted diseases.
(c) The values displayed by Mamta and her husband are :
(i) Awareness (or knowledge) that various birth control methods are available to prevent pregnancy and limit the size of family.
(ii) Concern for the health of woman (because too many pregnancies spoil the health of woman or mother).
(iii) Concern for the future of children (because good facilities and best education can be provided only if the number of children is less).
(iv) Responsible citizens (because they do not want to increase country’s population too much and put pressure on its limited resources).

Question. Vidya is a married woman who has a cleft chin (a deep hollow in her chin). Vidya has recently been blessed with a baby girl who has also a cleft chin. Anita is a close friend of Vidya. When she learnt that Vidya’s baby girl also has a cleft chin like Vidya, she got worried. This is because Anita has a huge scar on her left cheek which remained permanently after she got a cut on the cheek during an accident which took place in her school days. Anita is worried that her baby (which is due shortly), may also have a scar on her left cheek just like her. One day, Anita’s niece Radha, who is a science student of class X, came to see her. Anita shared her apprehension with Radha. Radha could understand her problem. She told Anita
that her case is entirely different from that of Vidya. Radha explained everything to Anita clearly. Anita was now very much relaxed.
(a) What is an acquired trait ?
(b) What is an inherited trait ?
(c) What type of trait is (i) cleft chin, and (ii) cheek scar ?
(d) Explain why, Vidya’s cleft chin has been passed on to her baby but Anita’s cheek scar cannot bepa ssed on to her baby.
(e) What values are displayed by Radha in this episode ?
Answer : (a) A trait (or characteristic) of an organism which is ‘not inherited’ but develops in response to the environment, is called an acquired trait. Acquired trait involves changes only in the non-reproductive cells of an organism and hence cannot be passed on to the next generation.
(b) A trait (or characteristic) of an organism which is caused by a change in the genes (or DNA) present in the reproductive cells (or gametes) of parent organism is called inherited trait. Inherited trait can be passed on to the next generation.
(c) (i) Cleft chin is an inherited trait.
(ii) Cheek scar is an acquired trait.
(d) Vidya’s cleft chin trait has been passed on to her baby because it is an inherited trait involving reproductive cells (or gametes). Anita’s cheek scar cannot be passed on to her baby because it is an acquired trait involving only non-reproductive body cells.
(e) The values displayed by Radha in this episode are (i) Awareness (or knowledge) of acquired traits and inherited traits (ii) Application of knowledge in real-life situations, and (iii) concern for the health of Anita during pregnancy (by reducing her tension).

Question. Mohan and Radha are husband and wife who live in a village. They are going to have their first baby.
Mohan has blonde hair (pale yellow hair) with genotype hh whereas Radha has black hair with genotype HH. A discussion started between Mohan and Radha whether their baby would have blonde hair (pale yellow hair) like father or black hair like mother. Bikram is Mohan’s nephew. He had come to meet his uncle (mama ji) Mohan in the village. Bikram, who is a science student of class 10 in a city school, was listening to their discussion. When Mohan and Radha could not come to a conclusion about the hair colour of their would-be baby, Bikram said that the baby would have black hair colour. He explained the reason for this to Mohan and Radha.
(a) What are the factors which transmit characteristics (or traits) from the parents to their baby ?
(b) Name the process through which these factors are transmitted from parents to their baby.
(c) Explain how Bikram could tell in advance that the baby to be born would have black hair colour like mother (and not blonde hair like father).
(d) What values are exhibited by Bikram in this episode ?
Answer : (a) The characteristics (or traits) are transmitted from the parents to their baby through genes present on their sex chromosomes.
(b) Sexual reproduction.
(c) (i) Mother’s (Radha’s) cells contain two dominant genes HH for black hair, so she has black hair.
(ii) Father’s (Mohan’s) cells contain two recessive genes hh for blonde hair, so he has blonde hair.
(iii) Baby will get one dominant gene H for black hair (from mother) and one recessive gene h for blonde hair (from father), so its genotype will be Hh and phenotype will be black hair.
(d) The values exhibited by Bikram in this episode are (i) Awareness (or knowledge) of the transmission of characteristics (or traits) from parents to progeny, and (ii) Application of knowledge in solving real-life problems.

Question. Rahul and his classmates toured some of the villages in North Indian States during the summer holidays.
They found that in this area there were many more boys than girls in the age group of up to 6 years.
Rahul and his friends then went to a small Government Hospital just outside a village. The doctor told them that in this area the birth of a girl child is considered a burden on the family. So, every family in the village wants to have only boys (or sons). He said that people of the village are going to private clinics in cities for getting the pre-natal (before birth) determination of sex done on pregnant women and if the foetus is of a girl child, it is aborted. Due to this illegal practice of selective abortions, child sex ratio is declining at an alarming rate and has created many social problems. The doctor also told that in many households, the women are harassed and tortured for giving birth to a girl child. The village elders blame only the woman for bearing the girl child. The doctor said that they are trying to change the mind set of village people at great personal risk but it will take a lot of time to get rid of this social evil.
(a) What term is used for the act of deliberately aborting the foetus if it is of a girl child ?
(b) What is child sex ratio ? Why is it declining rapidly ?
(c) Why is the birth of a girl child considered a burden in the family ?
(d) In our society, the woman (or wife) is blamed for giving birth to a girl child. Prove scientifically that it is actually the man (or husband) who is responsible for the birth of a girl child.
(e) State an ill effect of this horrific practice of selective abortions in the long run.
(f) How can this evil of killing girl child even before her birth can be prevented ?
Answer : (a) The act of deliberately aborting the foetus if it is of a girl child, is called female foeticide. (The deliberate termination of a woman’s pregnancy is called abortion).
(b) Child sex ratio is the number of girls per thousand boys in human population of an area between the age group of 0 to 6 years. Child sex ratio is declining rapidly due to female foeticide.
(c) The demand of dowry during the marriage of a girl is the main reason for thinking that the birth of a girl child is burden on the family.
(d) Half of the man’s sperms have X sex chromosomes whereas the other half sperms have Y sex chromosomes.
On the other hand, all the ova (or eggs) of woman have only X sex chromosomes. Now, a girl child is conceived when the sperm of man carrying X chromosome fertilises the ovum (or egg) of woman carrying X chromosome. It is clear that man (or husband) is responsible for the birth of a girl child and not the wife (because only man has Y sex chromosome in half of his sperms which is required to have a male child or boy).
(e) An ill effect of female foeticide in the long run is that sufficient number of young girls is not available in the area to marry off all the boys in this age group. Due to this shortage of girls, brides are even bought and sold for this purpose.
(f) Female foeticide can be prevented :
(i) by strict implementation of laws to prohibit pre-natal determination of sex, to stop female foeticideand  dowry system.
(ii) by spreading awareness that no society can run or flourish without girls.
(iii) by providing free and compulsory education to girls and reservation in certain professions (such as teaching) so that they can become financially independent.

Question. Mr. Sharma had a complete medical check-up a few days back. The doctors diagnosed him to be HIVpositive (HIV+ve). This news spread like wildfire in the colony where he lives and also in the office where he works. The neighbours and colleagues who used to greet him with handshakes and warm hugs now tried to shun him (avoid him). They were reluctant to shake hands with him or hug him. Even Mr. Sharma’s own family became indifferent towards him and started treating him badly. Mr. Sharma felt neglected and isolated by all the people around him. He went into depression. A good neighbour, Mr. Mukesh, noted that Mr. Sharma was under a lot of depression because of HIV infection. So, Mr. Mukesh met the family of Mr. Sharma and explained them all about HIV infection. He told them that HIV infection can be treated with drugs and kept under control. He also clarified various myths about HIV and AIDS. (a) What is HIV ? What is meant by saying that Mr. Sharma is HIV-positive (HIV+ve) ?
(b) What are the various ways in which HIV can be transmitted ?
(c) Can HIV be contracted by shaking hands with or hugging a person infected with HIV ? Do you think HIV is the same as AIDS ?
(d) What are the various ways of protection from HIV infection ?
(e) Do you think people’s indifference towards HIV infected person Mr. Sharma is justified ? How should we behave with such persons ?
(f) What values are displayed by Mr. Mukesh in this episode ?
Answer : (a) HIV stands for Human Immunodeficiency Virus. HIV-positive means that the person has HIV infection.
(b) HIV can be transmitted :
(i) by having unprotected sex (without condom) with an HIV infected person.
(ii) by the transfusion of HIV infected blood.
(iii) by using HIV infected needles and syringes for injections.
(iv) from HIV infected mother to child during pregnancy and breastfeeding.
(c) No, HIV infection cannot be contracted by shaking hands or hugging a person infected with HIV. There is no harm in staying and working with an HIV-positive person. HIV is not the same as AIDS. HIV is the virus that leads to AIDS. A person can have HIV virus for many, many years without having AIDS disease.
Being HIV positive does not mean that the person has AIDS disease.
(d) A person can protect himself from HIV infection :
(i) by having safe sex by using a condom.
(ii) by ensuring that any blood needed by him is tested for HIV infection.
(iii) by using new and disposable needles and syringes for getting injections.
(iv) by getting tested for sexually transmitted diseases (including HIV).
(e) The people’s indifference (or rudeness) towards the HIV-positive Mr. Sharma is highly unjustified. Our behaviour towards an HIV+ve person should be full of sympathy and concern for his suffering and misfortune. We should help him to come out of depression and encourage him to lead a normal life by taking all the available drugs to control this infection.
(f) The values displayed by Mr. Mukesh are (i) Awareness (or knowledge) that HIV infection can be treated with drugs and kept under control, and that being HIV positive is not the same as having AIDS disease, and (ii) Compassion (sympathy and concern for the sufferings of others).

Question.  Budh Ram and Satto are husband and wife who live in a village. They already have two children in the form of two lovely daughters. During third pregnancy, Budh Ram and Satto went to a city clinic and, after paying a hefty bribe, got the pre-natal scan done on the foetus. After knowing the sex of foetus, they went to a famous lady doctor who specialises in gynaecology and requested her to carry out the medical termination of pregnancy. They offered her big money for doing this job. The lady doctor said a firm ‘No’. When the couple insisted, the doctor threatened to call the police and get them arrested.
(a) What type of scan was done to know the pre-natal (before birth) sex of foetus illegally ?
(b) What do you think this scan showed ?
(c) Why did Budh Ram and Satto want to terminate this pregnancy ?
(d) What term is used specifically for such type of termination of pregnancy ?
(e) What values were displayed by the lady doctor ?
Answer : (a) An ultrasound scan was done to know the sex of foetus.
(b) The ultrasound scan showed that it was a female foetus.
(c) Budh Ram and Satto wanted to terminate this pregnancy so as to abort the female foetus (foetus of the
girl child). This is because they wanted to try again for having a boy child (or son).
(d) Female foeticide.
(e) The values displayed by the lady doctor are :
(i) Awareness (or knowledge) that it is against the law to abort a female foetus (foetus of the girl child).
(ii) Concern for the girl child.
(iii) Responsibility towards society (to maintain healthy child sex ratio).
(iv) Honesty (in not accepting bribe).

Question. Shivani visited her village with her parents during the winter holidays. When she went to the fields outside the village, she saw a farmer spraying pesticides over the standing crops in the fields. When she looked at the container of pesticide lying on the ground, she knew that it was a pesticide which had been banned from use in most of the countries. The farmer was spraying pesticide without taking any precautions. Shivani asked the farmer to cover his nose and mouth properly with a cloth while spraying the pesticide. She also asked him not to spray too much pesticide on the crops because it is harmful to human beings, other animals and aquatic life in the long run. Shivani educated the farmer about the various harmful effects of this pesticide.
(a) What are pesticides ? Why are pesticides sprayed over the crops ? Which pesticide was being sprayed by the farmer on the crops ?
(b) (i) At which trophic level pesticides enter a food chain ?
(ii) At which trophic level of food chain, the concentration of pesticides is the maximum ?
(c) What name is given to the process of concentration of pesticides in the body of living organisms at each trophic level of a food chain ?
(d) Why do pesticides get accumulated at each trophic level in a food chain ?
(e) What are the harmful effects of the pesticide being sprayed by this farmer ?
(f) What values are displayed by Shivani in this episode ?
Answer : (a) Pesticides are the poisonous chemical substances which are sprayed over the standing crop plants to mprotect them from pests (harmful small animals) and diseases. The farmer was spraying DDT pesticide on the crops.
(b) (i) The pesticides enter a food chain at the first trophic level called producer level (which are the plants).
(ii) The concentration of pesticides is the maximum at the highest trophic level of organisms in a food chain (which occurs on the extreme right side in a food chain).
(c) Biological magnification.
(d) Pesticides get accumulated at each trophic level in a food chain because they are non-biodegradable chemical substances (which cannot be decomposed naturally by various micro-organisms present in soil and water bodies).
(e) DDT damages liver, nervous system and reproductive system in human beings. DDT can also cause various types of cancers, including liver cancer.
(f) The values displayed by Shivani are (i) Awareness (that DDT is harmful to human beings and other animals) (ii) Concern for the farmer (that DDT may not enter his respiratory system and damage it), and (iii) Concern for the environment (because DDT is non-biodegradable pesticide and persists in the soil and water bodies for a very long time).

Question. Diya has just moved into a new house in another colony alongwith her parents. Diya is a keen observer of all the human activities going around her in the colony. She noticed that in the colony people threw the left-over food, and fruit and vegetable peels into overflowing garbage bins to be taken away by the staff of Municipal Corporation. She also saw that the gardener of the colony collected all the fallen leaves of houseplants and garden plants in one corner of the park, let them dry, and ultimately burnt them. It was brought to her knowledge that Residents Welfare Association of the colony spent a lot of money every year in purchasing chemical fertiliser for the garden plants and grass lawns. Keeping all
this in view, Diya presented a plan of action to the President of Welfare Association. On the successful completion of this plan after a few months, there was no need to purchase chemical fertiliser anymore.
The environment also looked very neat and clean.
(a) What do you think was Diya’s plan of action ?
(b) How did Diya’s plan of action help the environment ?
(c) How did Diya’s plan of action help the Residents Welfare Association ?
(d) What values of Diya are displayed by this plan of action ?
Answer : (a) Diya used the left-over food, fruit and vegetable peels and fallen leaves collected from the whole colony for making compost.
(b) The left-over food, and fruit and vegetable peels which used to rot in garbage bins and emit foul smell were now buried in the compost pit. Similarly, the fallen plant leaves which used to remain scattered here and there, and produced lot of smoke on burning, were now buried in compost pit. These actions helped in keeping the environment neat and clean.
(c) A lot of money which was earlier spent by Residents Welfare Association in purchasing the chemical fertiliser for the garden plants and grass lawns was saved. This is because the compost made in the colony itself was now used as manure to grow plants in the garden as well as in lawns.
(d) The values displayed by Diya are (i) Awareness (that waste materials such as left-over food, fruit and vegetable peels, and fallen leaves of plants can be converted into a useful material called compost)(ii) Concern for the environment (to keep it clean and protect it from the har mful effects of using chemical fertilisers), and (iii) Desire to help Residents Welfare Association (by saving money spent on fertilisers).

Question. Mr. Bhatia wanted to buy a new refrigerator and a new air conditioner in place of old ones which were purchased ten years ago. When Mr. Bhatia went to the market to buy these items his son Ankit, who is a student of tenth standard, also went with him. Before buying the new refrigerator and air conditioner, Ankit asked the various details from the shopkeeper and made sure that they did not contain old refrigerant which was not environment-friendly. The shopkeeper told him that these items now work with the new, eco-friendly refrigerant. Mr. Bhatia was puzzled by all this discussion. When they reached home, Ankit explained everything to his father. Ankit’s father was happy at his choice.
(a) What do you think were the old refrigerants used in earlier refrigerator and air conditioner ?
(b) What was the harmful effect of old refrigerants to the environment if they leaked out ?
(c) What diseases could have been caused if people of the whole world had continued to use old
refrigerants ? Why ?
(d) Name the new refrigerant which is being used increasingly in place of old one.
(e) Why is the new refrigerant being used these days not harmful to the environment ?
(f) What values are displayed by Ankit in this episode ?
Answer : (a) CFCs (Chloro-Fluoro-Carbons).
(b) CFCs are ozone depleting substances. So, if CFCs leaked out from refrigerators or air conditioners, they would attack the protective ozone layer high up in the atmosphere and destroy it gradually.
(c) If the people of whole world continued to use CFCs, then more and more of protective ozone layer in the upper atmosphere could be damaged, allowing more and more harmful ultraviolet radiations coming from the sun to pass through it and reach the earth. These ultraviolet radiations could cause diseases such as skin cancer, eye cataract, and damage the immune system by lowering the body’s resistance to diseases.
(d) HFCs (Hydro-Fluoro-Carbons).
(e) The new refrigerants (HFCs) do not attack or destroy the protective ozone layer in the upper atmosphere.
So, they are not harmful to the environment.
(f) The values displayed by Ankit are (i) Awareness (or knowledge) that ozone-friendly refrigerants (HFCs) are now available which can be used in place of harmful CFCs, and (ii) Desire to protect the useful ozone layer and prevent the harmful effects of ozone depletion.

Question. The teacher had just finished the chapter on environment in her class X lecture. She then placed four types of carry bags on the table in the classroom. These were cloth carry bag, paper carry bag, polythene carry bag and jute carry bag. The teacher asked Anushka to choose any two bags which she thinks are the most environment-friendly. Anushka thought for a while and then picked up cloth carry bag and jute carry bag.
(a) Explain why, Anushka did not choose the polythene carry bag though it is long lasting and waterproof ?
(b) What is the reason for not choosing the paper bag ?
(c) Why did Anushka choose only cotton cloth bag and jute bag ?
(d) What values are displayed by Anushka in making her choices ?
Answer : (a) Anushka did not choose a polythene carry bag because polythene is a plastic which is a non-biodegradable material. Polythene bags lie scattered here and there and cause a lot of pollution. It is also not possible to dispose of old polythene bags by burning because they produce extremely harmful gases on burning.
(b) Anushka did not choose the paper bag because though paper is biodegradable material but it is made from wood for which many forest trees have to be cut down regularly. So, Anushka did not choose paper bag to save trees by preventing deforestation.
(c) Anushka chose cloth bag and jute bag because cloth bag is made of cloth which comes from cotton crop grown in fields. Similarly, jute for making jute bag is obtained from jute crop grown in fields by the farmers. Since both cotton and jute are grown as crops in fields and they are biodegradable too, therefore, making of cloth bag and jute bag does not harm the environment in any way.
(d) The values displayed by Anushka are (i) Awareness (or knowledge) of biodegradable and nonbiodegradable materials, and (ii) Concern for the environment.

Question. Apoorva is a student of tenth class. She has asked her father to replace all the old filament-type bulbs in her house by CFLs. She herself uses a bicycle for going to her school. Apoorva has a habit of writing on both the sides of her notebook pages and never tears away pages from notebooks. One day when Apoorva went to the village fields alongwith her father, she saw two snakes in the standing crops. The farmers wanted to kill these snakes but Apoorva requested them not to do so. While at home or school, Apoorva is very particular to get the leaking taps repaired by the plumber immediately.
(a) What really is conserved when Apoorva uses CFLs in her house instead of filament-type bulbs ?
(b) What really is conserved when Apoorva goes to her school on bicycle ?
(c) What really is conserved when Apoorva writes on both sides of the pages in her notebook ?
(d) What really is conserved when Apoorva does not allow the snakes in standing crop fields to be killed ?
(e) What is conserved when Apoorva gets the leaking taps repaired immediately ?
(f) What are the things conserved by Apoorva commonly known as ?
(g) What values are displayed by Apoorva by her actions ?
Answer : (a) Coal (because coal is used to produce electricity).
(b) Petroleum (because a petroleum product ‘petrol’ is used in going to school by car or scooter).
(c) Forests (because paper used in making notebook is obtained from wood of forest trees).
(d) Wildlife (because snake is a part of wildlife which is a friend of the farmer).
(e) Water (because leaking taps waste water).
(f) Natural resources.
(g) The values displayed by Apoorva are (i) Management of natural resources (or conservation of natural resources) because coal, petroleum, forests and wildlife, and water are all natural resources, and (ii) Concern for a healthy environment.

Question. Mohan, Rohan and Sohan are three classmates. They have three different habits. Mohan is fond of taking bread and apple jam. Whenever all the jam of the container is eaten up by him, Mohan cleans the container thoroughly and puts iodised salt in it which his mother keeps on the kitchen rack. Rohan has a habit of putting old notebooks, newspapers and magazines at one place and sell it to Kabadiwala after a month to make some extra pocket money. Sohan has also a unique habit of going from room to room in his big house and switch off the lights and fans when no one is in the rooms. Actually, Mohan, Rohan and Sohan are collectively trying to practise three R’s taught by their teacher in their own ways.
(a) What is meant by three R’s ? In which context are they used ?
(b) Which of the three R’s is exemplified by Mohan’s action ?
(c) Which of the three R’s is exemplified by Rohan’s action ?
(d) Which of the three R’s is exemplified by Sohan’s action ?
(e) Why is the R exemplified by Mohan’s action better than the R exemplified by Rohan’s action ?
(f) What values are displayed by Mohan, Rohan and Sohan in this episode ?
Answer : (a) The three R’s stand for Reduce, Recycle and Reuse. These are used in the context of natural resources.
(b) Mohan reuses the empty jam container for storing iodised salt, so the R exemplified by Mohan’s action is ‘Reuse’.
(c) Rohan sells old paper products such as old notebooks, newspapers and magazines to kabadiwala for being sent to paper mills for recycling (making new paper), so the R exemplified by Rohan’s action is ‘Recycle’.
(d) Sohan switches off lights and fans when not needed to avoid wastage of electricity and reduces the consumption of coal (which is usually used to produce electricity), so the R exemplified by Sohan’s action is ‘Reduce’.
(e) We have just seen that Mohan practises ‘reuse’ and Rohan practises ‘recycle’. The process of ‘reuse’ is better than that of recycling because though some energy is used to recycle old objects but no energy is required during reuse.
(f) The values displayed by Mohan, Rohan and Sohan are : (i) Awareness (or knowledge) of 3 R’s to save the environment, and (ii) Ability to use their knowledge in everyday situations.

1.Mention the two most common methods of asexual reproduction in animals?

2.Name two organisms which reproduce by binary fission?

3.A-sexual reproduction takes place through budding in :

(a)Amoeba (b) Yeast (c)Plasmodium (d) Leishmania

4.The anther contains:

(a)Sepals (b) Ovules (c) Carpel (d) Pollen grains

5.What technical term is given to the future shoot and future root in the embryo in a seed?

6.Name the scientist who established the laws of inheritenance?

7.Define inheritenance?

8.Write the scientific term used for the science of heredity and variation?

9.What is a dominant trait?

10. What is a recessive trait?

11.What is meant by the term ‘environment’ ?

12.Name any 2 non- biodegradable substances?

13.Name any 2 biodegradable substances?

14.Name 2 constituents of biotic environment?

15. Name 1 constituent each of biotic and abiotic environment?

16.Which of the following is not a part of biotic community?

(a) Algae (b) Mushroom (c) Moss (d) Water

17. Give the scientific term for organisms which feed directly on plants?

18.Name any 2 omnivores?

19.Give an example of 3 step food chain operating in grassland?

20.Write an aquatic food chain?