Natural Resources, Biology, Class - IX

1. How is our atmosphere different from the atmospheres on Venus and Mars?

Ans:- Earth’s atmosphere is different from those of Venus and Mars. This difference lies essentially in their compositions. Earth’s atmosphere is a mixture of nitrogen (79%), oxygen (20%), and a small fraction of carbon dioxide, water vapours and other gases. This makes the existence of life possible on Earth. However, the atmospheres on Venus and Mars mainly consist of carbon dioxide. The amount of carbon dioxide on these planets can range from 95% to 97%.

2. How does the atmosphere act as a blanket?

Ans:- The atmosphere acts as a blanket by performing the following functions:

(a) It keeps the average temperature of the Earth fairly constant during day time and even during the course of whole year.

(b) It prevents a sudden increase in the temperature during day time.

(c) It slows down the escape of heat from the surface of the Earth into outer space during night time.

3. What causes winds?

Ans:- An uneven heating of the Earth’s surface causes winds. On being heated, air becomes lighter and rises up. As a result, a region of low pressure is created. Then, air from a high pressure region moves to a low pressure region, causing wind.

4. How are clouds formed?

Ans:- During day time, on being heated, a large amount of water evaporates from various water bodies and goes into the air. A part of this water vapour also reaches the atmosphere through biological activities such as transpiration and respiration. This causes the air in the atmosphere to heat up. When this heated air rises, it expands and cools, which results in the condensation of water vapour forming water droplets. The presence of dust and other suspended particles in air also facilitates the process of condensation. The formation of water droplets leads to the formation of clouds.

5. List any three human activities that you think would lead to air pollution.

Ans:- The following three human activities would lead to air pollution:

(i) Burning of fossil fuels such as coal and petroleum

(ii) Industrialization

(iii) Deforestation

6. Why do organisms need water?

Ans:- Organisms need water for the following reasons:

(i) All cellular processes need water as a medium. Usually, the reactions that take place in our body or within the cells occur between substances that are dissolved in water.

(ii) Since most of the substances are transported in a dissolved form, water is necessary.

7. What is the major source of fresh water in the city/town/village where you live?

Ans:- River is a major source of fresh water.

8. Do you know of any activity which may be polluting this water source?

Ans:- The discharge of waste water from homes, industries, hospitals, etc. into the river pollutes this fresh water source.

9. How is soil formed?

Ans:- Soil is formed by breaking down of rocks at or near the surface of the Earth through various physical, chemical, and biological processes by various factors such as the sun, water, wind, and living organisms.

(i) Sun:

During day time, the rocks are heated. This causes the rocks to expand. During night time, these rocks cool down and contract. Since all parts of the rock do not undergo expansion and contraction at the same rate, this causes the formation of cracks in these rocks. These cracks lead to the breaking up of huge rocks into smaller pieces.

(ii) Water:

Water catalyses the process of formation of soil in two ways.

(a) Water goes into the cracks and crevices formed in the rocks. When this water freezes, its volume increases. As a result, the size of the cracks also increases. This helps in the weathering of rocks.

(b) Running water wears away hard rocks over long periods of time. Water moving in fast speed carries big and small particles of rock downstream. These rocks rub against each other, resulting in breaking down of rocks. These smaller particles are carried away by running water and deposited down its path.

(iii) Wind:

Strong winds carry away rocks, which causes rubbing of rocks. This results in the breaking down of rocks into smaller and smaller particles.

(iv) Living organisms:

Some living organisms like lichens help in the formation of soil. Lichens also grow on rocks. During their growth, lichens release certain substances, which cause the rock surface to powder down forming a thin layer of soil. On this thin layer of soil, some small plants like moss also grow. They further cause the breaking down of the rock particles.

10. What is soil erosion?

Ans:- The blowing away or washing away of land surface by wind or water is known as soil erosion.

11. What are the methods of preventing or reducing soil erosion?

Ans:-The methods of preventing or reducing soil erosion are:

(i) Prevention of deforestation

(ii) Plantation of trees

12. Why is the atmosphere essential for life?

Ans:- The atmosphere is essential for life because it maintains an appropriate climate for the sustenance of life by carrying out the following activities:

(i) Atmosphere keeps the average temperature of the Earth fairly constant during day time.

(ii) It prevents a sudden increase in temperature during day time.

(iii) It also slows down the escape of heat from the surface of the Earth into outer space during night time.

13. Why is water essential for life?

Ans:- Water is essential for life because of the following reasons:

(i) Most biological reactions occur when substances are dissolved in water. Thus, all cellular processes need water as a medium to take place.

(ii) Transportation of biological substances needs water as a medium.

14. How are living organisms dependent on the soil? Are organisms that live in water totally independent of soil as a resource?

Ans:- Almost all living organisms are dependent on soil. Some depend directly, while some depend indirectly.

Plants need soil for getting support as well as nutrients to prepare their food.

On the other hand, organisms depend on plants for food and other substances that are essential for life.

Herbivores depend directly upon plants, and carnivores depend upon animals, which in turn depend upon plants for food. This makes them depend on soil indirectly.

Organisms that live in water are not totally independent of soil as a resource. These organisms depend on aquatic plants for food and other substances. These aquatic plants in turn require minerals for their sustenance. These minerals are carried to water bodies from soil by rivers, rain water, etc. Without the supply of minerals from the soil to the water bodies, it is impossible to imagine aquatic life.

15. You have seen weather reports on television and in newspapers. How do you think we are able to predict the weather?

Ans:- The meteorological department of the government collects data on the elements of weather such as maximum and minimum temperatures, maximum and minimum humidity, rainfall, wind speed, etc. They are able to study these elements using various instruments. The maximum and minimum temperature of a day is measured by a thermometer known as the maximum−minimum thermometer. Rain fall is measured by an instrument known as the rain gauge. Wind speed is measured by anemometers. There are various instruments used to measure humidity.

16. We know that many human activities lead to increasing levels of pollution of the air, water-bodies and soil. Do you think that isolating these activities to specific and limited areas would help in reducing pollution?

Ans:- Yes. Isolating human activities to specific areas would help in reducing levels of pollution. For example, setting up of industries in isolated regions will control pollution to some extent. The pollution caused by these industries will not contaminate water resources, agriculture land, fertile land, etc.

17. Write a note on how forests influence the quality of our air, soil and water resources.

Ans:- Forests influence the quality of our air, soil, and water resources in various ways. Some of them are:

(i) Forests balance the percentages of carbon dioxide and oxygen in the atmosphere. The increasing amount of carbon dioxide caused by human activities is balanced by a larger intake of carbon dioxide by plants during the process of photosynthesis. Simultaneously, a large amount of oxygen is released.

(ii) Forests prevent soil erosion. Roots of plants bind the soil tightly in a way that the surface of the soil cannot be eroded away by wind, water, etc.

(iii) Forests help in the replenishment of water resources. During the process of transpiration, a huge amount of water vapour goes into the air and condenses to form clouds. These clouds cause rainfall that recharge water bodies.

Improvement in Food Resources, Biology Class - IX

 

1. What do we get from cereals, pulses, fruits and vegetables?

Ans:- (i) Cereals provide us with carbohydrates. Also, they are a rich source of energy.

(ii) Pulses give us proteins.

(iii) Fruits and vegetables are a rich source of vitamins and minerals. A small amount of proteins, carbohydrates, and fats are also present in them.

2. How do biotic and abiotic factors affect crop production?

Ans:- A variety of biotic factors such as pests, nematodes, diseases, etc. can reduce the net crop production. A pest causes damage to agriculture by feeding on crops. For example, boll weevil is a pest on cotton. It attacks the cotton crop, thereby reducing its yield. Weeds also reduce crop productivity by competing with the main crop for nutrients, light, and space.

Similarly, abiotic factors such as salinity, temperature, etc. affect the net crop production. Some natural calamities such as droughts and floods are unpredictable. Their occurrence has a great impact on crops sometimes, destroying the entire crop.

3. What are the desirable agronomic characteristics for crop improvements?

Ans:- The desirable agronomic characteristics for crop improvements are:

(i) Tallness and profuse branching in any fodder crop.

(ii) Dwarfness in cereals.

These desirable agronomic characteristics help in increasing crop productivity.

4. What are macro-nutrients and why are they called macro-nutrients?

Ans:- Macro-nutrientsare nutrients required in relatively large quantities for growth and development of plants. They are six in number. Since they are required in large quantities, they are known as macro-nutrient. The six macro-nutrients required by plants are nitrogen, phosphorus, potassium, calcium, magnesium, and sulphur.

5. How do plants get nutrients?

Ans:- Plants require sixteen essential nutrients from nature for their growth and development. All these nutrients are obtained from air, water, and soil. Soil is the major source of nutrients. Thirteen of these nutrients are available from soil. The remaining three nutrients (carbon, oxygen, and hydrogen) are obtained from air and water.

6. Compare the use of manure and fertilizers in maintaining soil fertility.

Ans:- Manures increase soil fertility by enriching the soil with organic matter and nutrients as it is prepared by the decomposition of animal excreta and plant wastes. On the other hand, fertilizers are mostly inorganic compounds whose excessive use is harmful to the symbiotic micro-organisms living in soil. Their excessive use also reduces soil fertility. Hence, fertilizers are considered good for only short term use.

7. Which of the following conditions will give the most benefits? Why?

(a) Farmers use high-quality seeds, do not adopt irrigation or use fertilizers.

(b) Farmers use ordinary seeds, adopt irrigation and use fertilizer.

(c) Farmers use quality seeds, adopt irrigation, use fertilizer and use crop protection measures.

Ans:- (c)Farmers using good quality seeds, adopting irrigation, using fertilizers, and using crop protection measures will derive most benefits.

(i) The use of good quality seeds increases the total crop production. If a farmer is using good quality seeds, then a majority of the seeds will germinate properly, and will grow into a healthy plant.

(ii) Proper irrigation methods improve the water availability to crops.

(iii) Fertilizers ensure healthy growth and development in plants by providing the essential nutrients such as nitrogen, phosphorus, potassium, etc.

(iv) Crop protection measures include various methods to control weeds, pests, and infectious agents. If all these necessary measures are taken by a farmer, then the overall production of crops will increase.

8. Why should preventive measures and biological control methods be preferred for protecting crops?

Ans:- Preventive measures and biological control methods should be preferred for protecting crops because excessive use of chemicals leads to environmental problems. These chemicals are also poisonous for plants and animals. Preventive measures include proper soil and seed preparation, timely sowing of seeds, intercropping and mixed cropping, usage of resistant varieties of crops, etc. On the other hand, biological control methods include the usage of bio-pesticides that are less toxic for the environment. An example of bio-pesticides is Bacillus thuringenesis,which is an insect pathogen that kills a wide range of insect larvae. Therefore, both preventive measures and biological control methods are considered eco- friendly methods of crop protection.

9. What factors may be responsible for losses of grains during storage?

Ans:- During the storage of grains, various biotic factors such as insects, rodents, mites, fungi, bacteria, etc. and various abiotic factors such as inappropriate moisture, temperature, lack of sunlight, flood, etc. are responsible for losses of grains. These factors act on stored grains and result in degradation, poor germinability, discolouration, etc.

10. Which method is commonly used for improving cattle breeds and why?

Ans:- Cattle farming is commonly used for improving cattle breeds. The purpose of cattle farming is to increase the production of milk and draught labour for agricultural work. Dairy animals (females) are used for obtaining milk and draught animals (males) are engaged in agricultural fields for labour work such as carting, irrigation, tilling, etc. Cross breeding between two good varieties of cattle will produce a new improved variety. For example, the cross between foreign breeds such as Jersey Brown, Swiss (having long lactation periods) and Indian breeds such as Red Sindhi, Sahiwal (having excellent resistance power against diseases) produces a new variety having qualities of both breeds.

11. Discuss the implications of the following statement:

“It is interesting to note that poultry is India’s most efficient converter of low fibre food stuff (which is unfit for human consumption) into highly nutritious animal protein food.”

Ans:- Poultry in India is the most efficient converter of low fibre food stuff into highly nutritious animal protein food. In poultry farming, domestic fowls are raised to produce eggs and chicken. For this, the fowls are given animal feeds in the form of roughage, which mainly consists of fibres. Thus, by feeding animals a fibre rich diet, the poultry gives highly nutritious food in the form of eggs and chicken.

12. What management practices are common in dairy and poultry farming?

Ans:- Common management practices in dairy and poultry farming are:

(i) Proper shelter facilities and their regular cleaning.

(ii) Some basic hygienic conditions such as clean water, nutritious food, etc.

(iii) Animals are kept in spacious, airy, and ventilated place.

(iv) Prevention and cure of diseases at the right time is ensured.

13. What are the differences between broilers and layers and in their management?

Ans:- Layersare meant for egg production, whereas broilers are meant for poultry meat. Nutritional, environmental, and housing conditions required by broilers are different from those required by egg layers. A broiler chicken, for their proper growth, requires vitamin rich supplements especially vitamin A and K. Also, their diet includes protein rich food and enough fat. They also require extra care and maintenance to increase their survival rate in comparison to egg layers.

14. How are fish obtained?

Ans:- Fish can be obtained by two ways:

(i) Capture fishing: It is the process of obtaining fish from natural resources.

(ii) Culture fishery: It is the practice of farming fishes. Farming can be done in both freshwater ecosystem (which includes river water, pond water) and marine ecosystem.

15. What are the desirable characters of bee varieties suitable for honey production?

Ans:- Bee varieties having the following desirable characters are suitable for honey production:

(i) They should yield high quantity of honey.

(ii) They should not sting much.

(iii) They should stay in the beehive for long durations.

(iv) They should breed very well.

16. What are the advantages of composite fish culture?

Ans:- An advantage of composite fish culture is that it increases the yield of fish. In a composite fish culture, five or six different species are grown together in a single fish pond. Fishes with different food habitats are chosen so that they do not compete for food among themselves. Also, this ensures a complete utilization of food resources in the pond. As a result, the survival rate of fish increases and their yield also increases.

17. What is pasturage and how is it related to honey production?

Ans:- Pasturage is the availability of flowers from which bees collect nectar and pollen. It is related to the production of honey as it determines the taste and quantity of honey.

18. Explain any one method of crop production which ensures high yield.

Ans:- Crop rotationis one of the methods of crop production that ensures high yield. It is the method of growing two or more varieties of crops on the same land in sequential seasons. A crop utilises some particular nutrients in larger quantities from the soil. Then, if the same crop is grown in subsequent seasons those nutrients will get depleted in the soil. Therefore, crops having different nutrient requirements are rotated. For example, legumes which have nitrogen-fixing bacteria in their root nodules supply the soil with nitrogen. Therefore, these legumes are rotated with nitrogen requiring cereals such as wheat and maize. This method reduces the need of fertilizers, thereby increasing the overall yield of crops.

19. Why are manures and fertilizers used in fields?

Ans:- Manures and fertilizers are used in fields to enrich the soil with the required nutrients. Manure helps in enriching the soil with organic matter and nutrients. This improves the fertility and structure of the soil. On the other hand, fertilizers ensure a healthy growth and development in plants. They are a good source of nitrogen, phosphorus, and potassium. To get an optimum yield, it is instructed to use a balanced combination of manures and fertilizers in the soil.

20. What are the advantages of inter-cropping and crop rotation?

Ans:- Inter-cropping and crop rotation both play an important role in increasing the yield of crops. Inter-cropping helps in preventing pests and diseases to spread throughout the field. It also increases soil fertility, whereas crop rotation prevents soil depletion, increases soil fertility, and reduces soil erosion. Both these methods reduce the need for fertilizers. It also helps in controlling weeds and controls the growth of pathogens and pests in crops.

21. What is genetic manipulation? How is it useful in agricultural practices?

Ans:- Genetic manipulationis a process where the gene for a particular character is introduced inside the chromosome of a cell. When the gene for a particular character is introduced in a plant cell, a transgenic plant is produced. These transgenic plants exhibit characters governed by the newly introduced gene.

For example, let us assume there is a wild plant that produces small fruits. If the gene responsible for a larger fruit size is introduced in this plant, this plant becomes transgenic, and starts producing larger fruits. Similarly, genes for higher yield, disease resistance, etc. can be introduced in any desired plant.

Therefore, gene manipulation plays an important role in agricultural practices. It helps in improving crop variety. It ensures food security and insect resistant crops. It also improves the quality and yield of crops.

22. How do storage grain losses occur?

Ans:- There are various biotic and abiotic factors that act on stored grains and result in degradation, poor germinability, discolouration, etc. Biotic factors include insects or pests that cause direct damage by feeding on seeds. They also deteriorate and contaminate the grain, making it unfit for further consumption. Abiotic factors such as temperature, light, moisture, etc., also affect the seed. They decrease the germinating ability of the seeds and make them unfit for future use by farmers. Unpredictable occurrence of natural calamities such as droughts and floods also causes destruction of crops.

23. How do good animal husbandry practices benefit farmers?

Ans:- Cattle farming is one of the methods of animal husbandry that is most beneficial for farmers. Using this method, better breeds of draught animals can be produced. Such draught animals are engaged in agricultural fields for labour work such as carting, irrigation, tilling, etc.

24. What are the benefits of cattle farming?

Ans:- Benefits of cattle farming:

(i) Good quality and quantity of milk can be produced.

(ii) Draught labour animals can be produced for agricultural work.

(iii) New variety that are resistant to diseases can be produced by crossing two varieties with the desired traits.

25. For increasing production, what is common in poultry, fisheries and bee-keeping?

Ans:- The common factor for increasing production in poultry, fisheries, and bee keeping is the proper management techniques that are to be followed. Regular cleaning of farms is of utmost importance. Maintenance of temperature and prevention and cure of diseases is also required to increase the number of animals.

26. How do you differentiate between capture fishing, mariculture and aquaculture?

Ans:-

Capture fishing	Mariculture	Aquaculture
It is the method of obtaining fishes from natural resources.	It is the culture of marine fishes for commercial use.	It involves the production of aquatic animals that are of high economic value such as prawns, lobsters, fishes, crabs, etc.

Why Do We Fall Ill, Biology, Class - IX

 

1. State any two conditions essential for good health.

Ans:- The twoconditions essential for good health are:

(i) An individual must have better health facilities and more professionals to deal with health problems.

(ii) All basic necessary conditions to prevent diseases must be present. For example, proper garbage collection and disposal, clearing of drains, supply of healthy drinking water, etc.

2. State any two conditions essential for being free of disease.

Ans:- The twoconditions essential for being free of diseases are:

(i) Personal hygiene and cleanliness are necessary to stay away from diseases.

(ii) Individuals should take a balanced diet that contains carbohydrates, fats, proteins, vitamins, fibres, and proper quantity of water.

3. Are the answers to the above questions necessarily the same or different? Why?

Ans:- No. The answers to the above questions may not necessarily be the same. This is because a disease free state is not the same as being healthy. Good health is the ability of an individual to realise his or her full potential. Individuals can have poor health without having any identifiable disease. Also, health is related to society and community, whereas having a disease is about an individual sick person. Hence, the conditions for good health and for being disease free can be same or even different.

4. List any three reasons why you would think that you are sick and ought to see a doctor. If only one of these symptoms were present, would you still go to the doctor? Why or why not?

Ans:- Symptoms such as a headache, stomach pain, nausea, vomiting, fever, etc., make us feel that we are sick and must visit a doctor. These symptoms basically indicate that there might be a disease, but we cannot predict the kind of disease. Therefore, it becomes necessary to visit a doctor so that the disease can be identified and can be treated with proper medication.

However, if only one of these symptoms is present, we usually do not visit a doctor. This is because such symptoms do not have much effect on our general health and ability to work. However, if a person is experiencing these symptoms for quite sometime, then he needs to visit a doctor for proper treatment.

5. In which of the following case do you think the long-term effects on your health are likely to be most unpleasant?

• If you get jaundice,

• if you get lice,

• If you get acne. Why?

Ans:- Jaundice is a disease that can cause long-term effects on our health. It is a chronic disease that lasts for a long period of time. Jaundice does not spread rapidly, but it develops slowly over a period of time.

6. Why are we normally advised to take bland and nourishing food when we are sick?

Ans:- We are normally advised to consume bland and nourishing food when we are sick so that we can get the nutrients and energy quickly to fight off the foreign disease- causing agents.

7. What are the different means by which infectious diseases are spread?

Ans:- Diseases can be spread through various means such as air, water, sexual contact, blood, and vector.

(i) Certain disease-causing micro-organisms are expelled in air by coughing, sneezing, talking, etc. These micro-organisms can travel through dust particles or water droplets in air to reach other people. For example, tuberculosis, pneumonia, etc. spread through air.

(ii) Sometimes causal micro-organisms get mixed with drinking water and spread water borne diseases. Cholera for example is water borne disease.

(iii) Sexual act between two people can lead to the transfer of diseases such as syphilis, gonorrhoea, AIDS, etc.

(iv) Certain diseases such as AIDS can spread via blood to blood contact during blood transfusion or pregnancy.

(v) Certain diseases spread by animals called vectors. For example mosquitoes spread malaria.

8. What precautions can you take in your school to reduce the incidence of infectious diseases?

Ans:- Precautions to reduce incidence of infectious diseases are:

(i) Stay away from the diseased person.

(ii) Cover your mouth or nose while coughing or sneezing to prevent the spread of disease.

(iii) Drink safe water.

(iv) Keep the environment clean to prevent mosquitoes from breeding.

9. What is immunization?

Ans:- Immunizationis defined as protection of the body from communicable diseases by administration of some agent that mimics the microbe. This suspension of killed microbes that mimics the disease-causing microbes is known as vaccine.

10. What are the immunization programmes available at the nearest health centre in your locality? Which of these diseases are the major health problems in your area?

Ans:- The immunization programmes available at the nearest health centre are DPT (Diphtheria, Pertusis, and Tetanus), polio vaccine, hepatitis B, MMR (Measles, Mumps, and Rubella), jaundice, typhoid, etc.

Of all these diseases, jaundice and typhoid are major health problems.

Exercice

1. How many times did you fall ill in the last one year? What were the illnesses?

(a) Think of one change you could make in your habits in order to avoid any of /most of the above illnesses.

(b) Think of one change you would wish for in your surroundings in order to avoid any of/most of the above illnesses.

Ans:- This varies from person to person. Some people fall ill several times in a year, while others do not fall ill at all. A person’s immune system and hygiene-related habits play a major role in determining the person’s health.

2. A doctor/nurse/health-worker is exposed to more sick people than others in the community. Find out how she/he avoids getting sick herself/himself.

Ans:- The following precautions must be taken by a doctor/ nurse/ health-worker:

(i) Wearing a mask when in contact with a diseased person.

(ii) Keeping yourself covered while moving around an infected place.

(iii) Drinking safe water.

(iv) Eating healthy and nutritious food.

(v) Ensuring proper cleanliness and personal hygiene.

3. Conduct a survey in your neighbourhood to find out what the three most common diseases are. Suggest three steps that could be taken by your local authorities to bring down the incidence of these diseases.

Ans:- Three most common diseases are:

(i) Tuberculosis

(ii) Typhoid

(iii) Jaundice

Steps to be taken to bring down the incidence of these diseases are:

(i) Proper disposal of sewage.

(ii) Ensuring supply of safe drinking water.

(iii) Providing a clean environment and preventing mosquitoes from breeding.

4. A baby is not able to tell her/his caretakers that she/he is sick. What would help us to find out

(a) that the baby is sick?

(b) what is the sickness?

Ans:- (a) The baby is sick can be determined by his/her behavioural changes such as constant crying of baby, improper intake of food, frequent mood changes, etc.

(b) The sickness is determined by symptoms or indications that can be seen in the baby. The symptoms include vomiting, fever, loose motion, paleness in the body, etc.

5. Under which of the following conditions is a person most likely to fall sick?

(a) when she is recovering from malaria.

(b) when she has recovered from malaria and is taking care of someone suffering from chicken-pox.

(c) when she is on a four-day fast after recovering from malaria and is taking care of someone suffering from chicken-pox.

Why?

Ans:- (c)A person is more likely to fall sick when she is on a four day fast after recovering from malaria and is taking care of someone who is suffering from chicken pox. This is because she is fasting during recovery, and her immune system is so weak that it is not able to protect its own body from any foreign infection. If she is taking care of someone suffering from chicken pox, then she has more chances of getting infected from chicken pox virus and will get sick again with this disease.

6. Under which of the following conditions are you most likely to fall sick?

(a) when you are taking examinations.

(b) when you have travelled by bus and train for two days.

(c) when your friend is suffering from measles.

Why?

Ans:- (c)You are more likely to fall sick when your friend is suffering from measles. This is because measles is highly contagious and can easily spread through respiration i.e., through air. Thus, if your friend is suffering from measles, stay away from him otherwise you might easily get infected with the disease.

Diversity in Living Organisms, Biology, Class - IX

 

 

1. Why do we classify organisms?
Ans :- There are a wide range of life forms (about 10 million −13 million species) around us. These life forms have existed and evolved on the Earth over millions of years ago. The huge range of these life forms makes it very difficult to study them one by one. Therefore, we look for similarities among them and classify them into different classes to study these different classes as a whole. Thus, classification makes our study easier.

2. Give three examples of the range of variations that you see in life-forms around you.
Ans:- Examples of range of variations observed in daily life are:
(i) Variety of living organisms in terms of size ranges from microscopic bacteria to tall trees of 100 metres.
(ii) The colour, shape, and size of snakes are completely different from those of lizards.
(iii) The life span of different organisms is also quite varied. For example, a crow lives for only 15 years, whereas a parrot lives for about 140 years.

3.Which do you think is a more basic characteristic for classifying organisms?
(a) The place where they live.
(b) The kind of cells they are made of. Why?
Ans :- The kind of cells that living organisms are made up of is a more basic characteristic for classifying organisms, than on the basis of their habitat. This is because on the basis of the kind of cells, we can classify all living organisms into eukaryotes and prokaryotes. On the other hand, a habitat or the place where an organism lives is a very broad characteristic to be used as the basis for classifying organisms. For example, animals that live on land include earthworms, mosquitoes, butterfly, rats, elephants, tigers, etc. These animals do not resemble each other except for the fact that they share a common habitat. Therefore, the nature or kind of a cell is considered to be a fundamental characteristic for the classification of living organisms.

4. What is the primary characteristic on which the first division of organisms is made?
Ans:-The primary characteristic on which the first division of organisms is made is the nature of the cell. It is considered to be the fundamental characteristic for classifying all living organisms. Nature of the cell includes the presence or absence of membrane-bound organelles. Therefore, on the basis of this fundamental characteristic, we can classify all living organisms into two broad categories of eukaryotes and prokaryotes. Then, further classification is made on the basis of cellularity or modes of nutrition.

5. On what basis are plants and animals put into different categories?

Ans:- Plants and animals differ in many features such as the absence of chloroplasts, presence of cell wall, etc. But, locomotion is considered as the characteristic feature that separates animals from plants. This is because the absence of locomotion in plants gave rise to many structural changes such as the presence of a cell wall (for protection), the presence of chloroplasts (for photosynthesis) etc. Hence, locomotion is considered to be the basic characteristic as further differences arose because of this characteristic feature.

6. Which organisms are called primitive and how are they different from the so-called advanced organisms?

Ans:- A primitive organism or lower organism is the one which has a simple body structure and ancient body design or features that have not changed much over a period of time. An advanced organism or higher organism has a complex body structure and organization. For example, an Amoeba is more primitive as compared to a starfish. Amoeba has a simple body structure and primitive features as compared to a starfish. Hence, an Amoeba is considered more primitive than a starfish.

7. Will advanced organisms be the same as complex organisms? Why?

Ans:- It is not always true that an advanced organism will have a complex body structure. But, there is a possibility that over the evolutionary time, complexity in body design will increase. Therefore, at times, advanced organisms can be the same as complex organisms.

8. What is the criterion for classification of organisms as belonging to kingdom Monera or Protista?

Ans:- The criterion for the classification of organisms belonging to kingdom Monera or Protista is the presence or absence of a well-defined nucleus or membrane-bound organelles. Kingdom Monera includes organisms that do not have a well-defined nucleus or membrane-bound organelles and these are known as prokaryotes. Kingdom Protista, on the other hand, includes organisms with a well-defined nucleus and membrane-bound organelles and these organisms are called eukaryotes.

9. In which kingdom will you place an organism which is single-celled, eukaryotic and photosynthetic?

Ans:- Kingdom Protista includes single celled, eukaryotic, and photosynthetic organisms.

10. In the hierarchy of classification, which grouping will have the smallest number of organisms with a maximum of characteristics in common and which will have the largest number of organisms?

Ans:- In the hierarchy of classification,a species will have the smallest number of organisms with a maximum of characteristics in common, whereas the kingdom will have the largest number of organisms.

11. Which division among plants has the simplest organisms?

Ans:- Thallophyta is the division of plants that has the simplest organisms. This group includes plants, which do not contain a well differentiated plant body. Their body is not differentiated into roots, stems, and leaves. They are commonly known as algae.

12. How are pteridophytes different from the phanerogams?

Ans:-

Pteridophyta	Phanerogams
They have inconspicuous or less differentiated reproductive organs.	They have well developed reproductive organs.
They produce naked embryos called spores.	They produce seeds.
Ferns, Marsilea, Equisetum, etc. are examples of pteridophyta.	Pinus, Cycas, fir, etc. are examples of phanerogams.

13. How do gymnosperms and angiosperms differ from each other?

Ans:-

Gymnosperm	Angiosperm
They are non-flowering plants.	They are flowering plants.
Naked seeds not enclosed inside fruits are produced.	Seeds are enclosed inside fruits.
Pinus, Cedar, fir, Cycas, etc. are some examples of gymnosperms.	Coconut, palm, mango, etc. are some examples of angiosperms.

14. How do poriferan animals differ from coelenterate animals?

Ans :-

Porifera	Coelenterate
They are mostly marine, non-motile, and found attached to rocks.	They are exclusively marine animals that either live in colonies or have a solitary life-span.
They show cellular level of organisation.	They show tissue level of organisation.
Spongilla, Euplectella, etc. are poriferans.	Hydra, sea anemone, corals, etc. are coelenterates.

15. How do annelid animals differ from arthropods?

Ans:-

Annelids	Arthropods
The circulatory system of annelids is closed.	Arthropods have an open circulatory system.
The body is divided into several identical segments.	The body is divided into few specialized segments.

16. What are the differences between amphibians and reptiles?

Ans:-

Amphibian	Reptiles
They have a dual mode of life.	They are completely terrestrial.
Scales are absent.	Skin is covered with scales.
They lay eggs in water.	They lay eggs on land.
It includes frogs, toads, and salamanders.	It includes lizards, snakes, turtles, chameleons, etc.

17. What are the differences between animals belonging to the Aves group and those in the mammalia group?

Ans:-

Aves	Mammals
Most birds have feathers and they possess a beak.	They do not have feathers and the beak is also absent.
They lay eggs. Hence, they are oviparous.	Some of them lay eggs and some give birth to young ones. Hence, they are both oviparous and viviparous.