Lakhmir Singh Solutions for Class 7 Science Chapter 1 Nutrition - PDF

Very Short Answer Type Questions

1. Name the pores through which leaves exchange gases.

Ans: Stomata, also called stomata, either multiple stomata, or minute openings or pores in the epidermis of leaves and young stems. Stomata are more on the underside of leaves.

2. Name the process by which plants make food.

Ans: Plants make food by the process called photosynthesis. Roots absorb water and minerals from the soil, and leaves absorb a gas called carbon dioxide (CO2) from the air. They use energy from sunlight to transform these ingredients into food. This process is called photosynthesis, which means "to make light".

3. What is photosynthesis?

Ans: Plants are called producers because they make or produce food. Roots absorb water and minerals from the soil, and leaves absorb a gas called carbon dioxide (CO2) from the air. They use energy from sunlight to transform these ingredients into food. This process is called photosynthesis, which means "to make light". Food is called glucose and starch.

4. State whether the following are true or false:

1. Carbon dioxide is released during photosynthesis.

2. Solar energy is converted into chemical energy during photosynthesis.

3. The product of photosynthesis is not a protein.

4. A plant having red leaves cannot do photosynthesis.

5. Plants which synthesise their food themselves are called saprotrophs.

Ans:

1. The following sentence is false.

2. The following sentence is true.

3. The following sentence is true.

4. The following sentence is false.

5. The following sentence is false.

5. Name any one plant which has nitrogen-fixing Rhizobium bacteria in its roots.

Ans: Gliricidia madri, a legitimate plant, has nitrogen-fixing rhizobia in its roots. Legumes can form symbiotic relationships with nitrogen-fixing soil bacteria called rhizobia. This symbiosis results in the formation of nodules in plant roots where bacteria can convert atmospheric nitrogen into ammonia that plants can use.

6. What do the patches of green layer floating on the surface of stagnant water bodies like ponds and takes consist of?

Ans: These floaters are nothing but the growth of mould and algae. These mainly contain spirogyra and tannins (phytoplankton), which give the water a green, brown or even red appearance.

7. Why are algae green?

Ans: Algae are green because they contain a lot of chlorophyll. Green algae vary in size and shape and include unicellular, colonial, filamentous, and tubular morphologies. Sexual reproduction is common, and gametes have two or four flagella.

8. 

1. Name a gas used in photosynthesis.

Ans: Plants absorb carbon dioxide (CO2) and water (H2O) from the air and soil.

2. Name a gas produced in photosynthesis.

Ans: The gas used is carbon dioxide. Photosynthesis gives glucose and oxygen as the final product. They release oxygen as a waste product during photosynthesis.

9. What name is given to those organisms.

1. Which can make their own food?

Ans: Organisms that prepare their food are called autotrophs. To do this, they rely on a process known as photosynthesis. Green plants are the best example of autotrophs.

2. Which depend on other organisms for food?

Ans: Heterotrophs are organisms that consume other organisms in the food chain. Organisms that cannot produce their food and instead derive their food and energy from ingesting organic matter, usually plant or animal matter, are heterotrophs. All animals, protozoa, fungi, and most bacteria are heterotrophs.

10. Rhizobium bacteria and leguminous plant help each other in survival. What is this relationship known as?

Ans: Legumes can form symbiotic relationships with nitrogen-fixing soil bacteria called rhizobia. This symbiosis results in the formation of nodules in plant roots where bacteria can convert atmospheric nitrogen into ammonia that plants can use.

11. What name is given to the relationship between an alga and fungus in lichens?

Ans: The relationship between an alga and fungus is a symbiotic relationship. The fungi provide the algae with water and minerals, which perform photosynthesis and provide nutrients to the fungi as sugars. Lichens do not grow in highly polluted environments, so they act as pollution indicators.

12. Where does the synthesis of food in a plant usually take place?

Ans: The synthesis of plant food takes place in the leaves. So all raw materials (water, carbon dioxide, sunlight) have to go there.

13. Why are the leaves of a plant usually green?

Ans: Chlorophyll gives leaves their green colour because they do not absorb the green wavelengths of white light. Plants reflect this wavelength of light, making them appear green.

14. Name the green pigment present in the leaves of a plant.

Ans: Chlorophyll is the pigment that gives plants their green colour and helps plants make their food through photosynthesis.

15. Name three plant nutrients commonly present in fertilisers and manures.

Ans: Most fertilisers commonly used in agriculture contain nitrogen, phosphorus and potassium, the three basic nutrients for plants.

16. Name the bacteria which convert nitrogen gas of air into nitrogen compounds.

Ans: Bacteria that convert atmospheric nitrogen into nitrogen compounds such as ammonia are called nitrogen-fixing bacteria.

17. What type of plants have Rhizobium bacteria in their root nodules?

Ans: Symbiotic plants like legumes can form symbiotic relationships with nitrogen-fixing soil bacteria called rhizobia. 

18. Name any two leguminous plants.

Ans: Well-recognised legumes are beans, soybeans, peas, chickpeas, peanuts, lentils, etc.

19. Name one autotrophic plant and one heterotrophic plant.

Ans: Green plants, algae, and some photosynthetic bacteria are examples of autotrophs. Cattle, buffalo, tigers, horses, and humans are examples of heterotrophs.

20. Name a parasitic plant with yellow, slender and tubular stem.

Ans: Parasitic plant with yellow thin tubular stems: Cuscuta is a parasitic plant with thin yellow tubular stems. Cuscuta is commonly known as Amar Bail in India.

21. Name a plant which has both autotrophic and heterotrophic modes of nutrition.

Ans: Carnivorous plants have both autotrophic and heterotrophic modes of nutrition.

22. Name one plant in which photosynthesis occurs in plant parts other than leaves. Name the plant part. 

Ans: Cacti are plants that carry out photosynthesis in their stems rather than their leaves.

23. Name four foods made by plants which are an important part of our diet.

Ans: Food grains, legumes, fruits and vegetables are all plant-based. Plants also provide different oils for cooking foods such as mustard oil, and sunflower oil.

24. The heterotrophic plants can be divided into two groups on the basis of their mode of nutrition. Name these two groups.

Ans: The heterotrophic plants can be divided into two groups based on their mode of nutrition are insectivorous plant symbiotic plants. 

25. Fill in the following blanks with suitable words:

1. Fungi like ……… and …….. are useful.

2. Saprotrophs secrete digestive juices on dead and decaying matter and convert it into a …….

3. The tiny spores of fungus plants are always present in ……..

4. In lichens, the chlorophyll containing partner is an ……..

5. The leather objects that are left in hot and humid weather for long are spoiled due to the growth of ……….

6. The food synthesised by plants is stored as ……..

7. In photosynthesis, solar energy is captured by the pigments called ………

8. During photosynthesis, plants take in ………. And release ………..

9. The gas produced during photosynthesis which is essential for the survival of all organisms is ………

10. The simplest carbohydrates made as food by photosynthesis is ……….

11. Crop plants require a lot of nitrogen to make ……….

12. The bodies of living organisms are made up of tiny units called ………

Ans: 

1. Fungi like mushroom and yeast are useful.

Explanation: Fungi, like yeast, are useful because they can ferment sweet liquids into wine or beer. Mushrooms are useful because they are edible and give us many things.

2. Saprotrophs secrete digestive juices on dead and decaying matter convert it into a solution. 

Explanation: Saprotrophs feed through a process known as absorptive feeding. In this process, food substrates (such as dead organisms and other abiotic organic matter) are directly digested by various enzymes secreted by saprotrophs.

3. The tiny spores of fungus plants are always present in air.

Explanation: Mould spores are always present in the air we breathe, but widespread mould contamination can cause health problems. Breathing mould can cause allergic and respiratory symptoms. 

4. In lichens, the chlorophyll containing partner is an alga.

Explanation: In lichens, chlorophyll-containing partners, algae, live symbiotically with fungi. The fungi provide the algae with shelter, water and minerals, and in return the algae provide the food they prepare through photosynthesis.

5. The leather objects that are left in hot and humid weather for long are spoiled due to the growth of fungus. 

Explanation: Fungal spores are airborne and grow on items that are exposed to hot and humid weather for extended periods (such as pickles, leather shoes, and clothing). During the rainy season, they land on moist and warm surfaces and germinate and grow.

6. The food synthesised by plants is stored as starch.

Explanation: The process of food production in plants is called photosynthesis, and it stores the synthesised food as carbohydrates (glucose and starch).

7. In photosynthesis, solar energy is captured by the pigments called chlorophyll.

Explanation: The role of chlorophyll in plants is to absorb light, usually sunlight. It transfers energy absorbed by light to two types of energy storage molecules. Through photosynthesis, plants use stored energy to convert carbon dioxide (got from the air) and water into glucose (a type of sugar).

8. During photosynthesis, plants take in carbon-di-oxide and release oxygen.

Explanation: They oxidise water in plant cells. Giving up electrons while carbon dioxide is being reduced. Receive electrons. Water turns into oxygen and carbon dioxide turns into glucose.

9. The gas produced during photosynthesis which is essential for the survival of all organisms is oxygen. 

Explanation: During photosynthesis, it produces oxygen. Oxygen released during photosynthesis is used by organisms to survive.

10. The simplest carbohydrates made as food by photosynthesis is glucose.

Explanation: Glucose carbohydrates are made up of three elements: carbon, hydrogen and oxygen. Plants use the simple carbohydrate glucose to make many other foods, including starches, oils (or fats), proteins, and vitamins.

11. Crop plants require a lot of nitrogen to make proteins. 

Explanation: Nitrogen is very important as it is a key component of chlorophyll, a compound that plants use sunlight energy to produce sugars from water and carbon dioxide. It is the main component of amino acids. 

12. The bodies of living organisms are made up of tiny units called cells.

Explanation: Living things are made up of cells. Cells are the basic structure of all living things. Cells make up the structure of the body, absorb nutrients from food, and perform vital functions. 

Short Answer type questions

26. Match the items given in column-I with those in column-II:

Ans: 

27. How would you test the presence of starch in leaves?

Ans: An iodine test can determine if the leaves contain starch. Boiling the leaves in alcohol and adding 2 drops of iodine solution to remove the chlorophyll from the leaves changes the colour to blue, indicating starch.

28. What is special about the leaves that they can synthesise food but other parts of a plant cannot?

Ans: Leaves have a green pigment called chlorophyll that helps them capture energy from sunlight and synthesise food. Other parts of the plant lack chlorophyll and therefore cannot synthesise food.

29. In addition to carbon dioxide and water, state two other conditions necessary for the process of photosynthesis to take place. 

Ans: The presence of sunlight and the green pigment chlorophyll are two other requirements for the process of photosynthesis.

30. Consider the following organisms: 

Lichen, mushrooms, Cuscuta, grass, pitcher plant

Out of these, which one is: 

1. An autotroph

2. A saprophyte

3. Symbiotic plant

4. A partial heterotroph 

5. A parasite

Ans: 

1. An autotroph - Grass

2. A saprophyte - Mushroom 

3. Symbiotic plant - Lichen

4. A partial heterotroph - Pitcher plant

5. A parasite - Cuscuta plant

31. Why do organisms need to take food? What are the two main modes of nutrition in organisms? 

Ans: Organisms need to ingest food to build and grow, repair damaged parts of their bodies, and get the energy to carry out their daily activities. The two main modes are autotrophic and heterotrophic feeding.

32. What is meant by an autotroph? Name one autotroph.

Ans: Algae are autotrophs along with plants and some bacteria and fungi. Autotrophs are producers in the food chain, meaning they create their nutrients and energy. Seaweeds, like most autotrophs, generate energy through a process called photosynthesis.

33. What is meant by a heterotroph? Give one example of a heterotroph.

Ans: Heterotrophs are called consumers because they are producers or other consumers that consume. Dogs, birds, fish, and humans are all examples of heterotrophs. Heterotrophs occupy the second and third level of the food chain, a series of organisms that provide energy and nutrients to other organisms.

34. Explain why, we cannot make food ourselves by photosynthesis like the plants do. 

Ans: The cells of our body lack the organelles present in plants, or chloroplasts. Chloroplasts contain a pigment called chlorophyll, which is necessary for photosynthetic reactions. In addition, plants breathe in O2 and emit CO2, which is the opposite of plants.

35. What are insectivorous plants? Name an insectivorous plant.

Ans: They are called carnivorous plants because insects are one of the most common prey for most carnivorous plants. Venus flytrap, pitcher plant, and cobra lily are some of the carnivorous plant names. They are often called carnivorous plants.

36. Why do farmers spread fertilisers and manures in the fields?

Ans: Managers and fertilisers are used in fields to supply the soil with plant nutrients and increase soil fertility to ensure vegetative growth, resulting in high crop production. It enriches the soil with nutrients, and organic matter and helps increase soil fertility.

37. What are plant parasites? Name one plant which is a parasite.

Ans: A parasitic plant is a plant that gets all or part of its food from another plant (the host) without contributing to the host's benefit, sometimes causing extreme harm to the host. Dodder (Cassytha spp., Cuscuta spp.) and red rattle (Odontites vernus) are generalised parasites.

38. What are saprophytes? Name one saprophyte.

Ans: Saprophytes are organisms that cannot produce food on their own. To survive, they feed on dead and decaying matter. Fungi and some bacteria are saprophytes. Examples of saprophytes are cheese mould and yeast.

39. Proteins are nitrogenous (nitrogen-containing) foods. How do plants get nitrogen for making proteins?

Ans: Plants get nitrogen through natural processes. It introduced nitrogen into the soil through manure and plant and animal debris. Bacteria in the soil convert nitrogen to ammonium and nitrate, which are taken up by plants through the process of nitrogen fixation.

40. 

1. Name the large, spherical structure usually located in the centre of a cell.

Ans: The nucleus is a large spherical structure present in almost all eukaryotic cells. It contains the genetic information of an organism as DNA. It is usually found in the centre of animal cells and peripherally in plant cells.

2. The nucleus in a cell is surrounded by a jelly-like material. Name the material. Ans: Inside the cell, a gelatinous substance surrounds the nucleus called the cytoplasm. It's mainly composed of cytoplasm of water, salt and protein. The cell membrane is the outer boundary that surrounds the cell.

3. Name the thin, outer covering which encloses a cell. 

Ans: The cell membrane, also called the plasma membrane, is a thin membrane that surrounds all living cells and separates them from the surrounding environment.

4. Name any two parts which are present in plant cells but not in animal cells. 

Ans: Plant cells have a cell wall, chloroplasts and other specialised plastids, and a large central vacuole that is not found in animal cells. The cell wall is a hard shell that protects the cell, provides structural support, and gives it shape.

Long Answer Type Questions

41. Give a brief description of the process of synthesis of food in green plants. What is chlorophyll? What is the role of chlorophyll in photosynthesis? 

Ans: Photosynthesis is a process performed by plants, algae, and some bacteria that harvests energy from sunlight to produce oxygen (O2) and chemical energy that is stored in glucose (a sugar). Herbivores get energy by eating plants, and carnivores get energy by eating herbivores. 

• Chlorophyll: Inside plant cells are small organelles called chloroplasts that store energy from sunlight. Within the thylakoid membrane of the chloroplast is a light-absorbing pigment called chlorophyll, which gives the green colour to plants. During photosynthesis, chlorophyll absorbs energy from blue and red light waves and reflects green light waves, making plants appear green.

• The role of chlorophyll in photosynthesis: The role of chlorophyll in plants is to absorb light, usually sunlight. It transfers energy absorbed by light to two types of energy storage molecules. 

• Through photosynthesis, plants use stored energy to convert carbon dioxide (got from the air) and water into glucose (a type of sugar). Plants use glucose along with nutrients from the soil to form new leaves and other plant parts. 

• Photosynthesis produces oxygen, which the plant releases into the air. 

• Chlorophyll gives plants their green colour because they do not absorb the green wavelengths of white light. Plants reflect this wavelength of light, making them appear green.

42. 

1. How do plants get carbon dioxide for making food by photosynthesis?

Ans: Plants take in the carbon dioxide they need for photosynthesis from the air. Plants absorb carbon dioxide gas from the air through tiny pores (called stomata) on the surface of their leaves (the singular word for stomata is stomata). In fact, the surface of plant leaves has countless tiny holes called stomata. A pair of guard cells surrounds each pore (or stoma). Guard cells control the opening and closing of stomata in leaves. Figure (a) shows open stomata and Figure (b) shows closed stomata. Carbon dioxide gas present in the air enters the leaves through the stomata on the surface of the plant leaves and is used for photosynthesis. It releases oxygen gas produced in the leaves during photosynthesis into the air through the same stomata. Leaf stomata open only when they need to take in carbon dioxide or release oxygen, and remain closed otherwise.

Tiny Pores Called Stomata are Present on the Surface of Leaves (One Pore is Called Stoma).

2. Explain how water and minerals are transported to the leaves of a plant to be used in food making by photosynthesis. 

Ans: Water and dissolved minerals from the soil reach plants through the roots. Many of the cells on the root surface contain root hairs. These protrusions increase the overall surface area and increase the root's ability to absorb more water. The process by which water enters the root is osmosis. When water enters the roots from the soil, it travels to the xylem vessels in the centre of the root. Xylem blood vessels carry water from the stem to the leaves of the plant. Leaves have a high concentration of dissolved minerals produced by photosynthesis and an overall low water concentration.

43. Describe briefly how nutrients are replenished in the soil? How is the growing of a leguminous crop in the fields beneficial to the farmer?

Ans: Phytonutrients such as nitrogen, phosphorus and potassium are naturally present in the soil. As plants grow, they absorb nutrients from the soil, further reducing the number of phytonutrients in the soil. For this reason, plant nutrients (or minerals) are replenished in the soil in two ways:

1. Nutrients are replenished in the soil by adding fertilisers and manures: Adding manure or compost to the soil in the field enriches the soil with nutrients such as nitrogen, phosphorus and potassium. Then the crops will grow well in this soil. Fertilisers and manures provide essential nutrients for plant growth so you can have healthy plants. The two most commonly used to supply plant nutrients (or minerals) two fields Fertilisers are NPK and urea. 

• NPK fertilisers provide nitrogen (N), phosphorus (P) and potassium (K) to the field soil, while urea only provides nitrogen.

• Field-grown crops need as much nitrogen as possible to make protein.

2.  Nitrogen can be replenished in the soil by growing Leguminous Crops: There is a lot of nitrogen gas in the air, but plants cannot use it. Plants need nitrogen as water-soluble compounds (such as nitrates). Plants such as gram (chana), peas, legumes (such as mung), and beans are called legumes (or legumes). Legumes have nodules containing rhizobia. 

• Rhizobium can convert atmospheric nitrogen gas into nitrogen compounds (such as nitrates). When legumes are grown in the field, root nodule bacteria in the legume tubers convert nitrogen gas from the air into nitrogen compounds such as nitrates. Legumes use some of these nitrogen compounds for their growth. 

• The remaining nitrogen compounds from the rhizobia mix with the soil of the field and enrich it. In this way, we naturally enriched the field soil with nitrogen compounds.

44. 

1. A person observes that some plants have deep red, violet and brown-coloured leaves. Can these leaves carry out photosynthesis? Give a reason for your answer. 

Ans: Deep red, purple, or brown leaves have these colours because of the presence of carotenoid or xanthophyll pigments. However, these leaves also contain the green pigment chlorophyll, which allows them to carry out photosynthesis. The colour of such leaves is not green because they have more carotenoids and xanthophyll pigments than chlorophyll, but photosynthesis continues anyway.

2. Describe the importance of photosynthesis for the existence of life on the earth. Ans: Photosynthesis is the main food source on earth. It releases oxygen, an essential element for the survival of life. Without photosynthesis, there would be no oxygen on earth. Chemical energy stored in plants flows into herbivores, carnivores, predators, parasites, decomposers and all life forms. It is a requirement of all higher forms on earth. 

• Photosynthesis fixes carbon dioxide and releases oxygen, reducing the greenhouse effect and global warming. The effect of carbon dioxide radiation from the Earth's atmosphere heating its surface. This causes the Earth's temperature to rise, melting ice caps and raising sea levels. Rising water levels pose a threat to coastal areas and islands. 

• Rising temperatures also cause biodiversity loss and habitat change. Plants consume carbon dioxide during photosynthesis, resulting in a temperature equilibrium on Earth. Planting trees can help further improve this balance.

45. 

1. What are the various modes of nutrition in plants? Give one example of each. 

Ans: Nutrients allow an organism to build its body, grow, repair damaged body parts, and provide energy to carry out life processes. This is how it is used inside the body. Autotrophic (auto = self; Trophos = food) Nutrition refers to the method of nutrition in which an organism produces its food from simple substances. Therefore, plants are called autotrophs. Animals and most other organisms consume food made by plants. They are called heterotrophs (heteros = other).

2. What do you understand by synthesis? Explain with an example.

Ans: Carbohydrates are made up of carbon, hydrogen and oxygen. They are used to synthesise other food components such as proteins and fats. But protein is a nitrogenous substance that contains nitrogen. 

• However, plants cannot absorb nitrogen in this form. There are certain bacteria in the soil that convert gaseous nitrogen into usable forms and release it into the soil. These are absorbed by plants along with water. You may also have seen how farmers put nitrogen-rich fertilisers into the soil. 

• In this way, along with other components, plants meet their nitrogen needs. Then plants can then synthesise proteins and vitamins.

Multiple Choice Questions (MCQs)

46. Which part of the plant gets carbon dioxide from air in photosynthesis?

1. Root hair 

2. Stomata 

3. Leaf veins

4. sepals

Ans: Correct option: b. Stomata

Explanation: Stomata gets the carbon dioxide from air in photosynthesis. Plants absorb carbon dioxide through tiny openings called stomata on the surface of leaves.

47. Plants take carbon dioxide from the atmosphere mainly through their:

1. Roots

2. Stems

3. Flowers

4. Leaves

Ans: Correct option: d. Leaves 

Explanation: Plants mainly absorb CO2 from the atmosphere through their leaves. Stomata are microscopic openings on the leaf surface. Stomata are tiny openings in the epidermis of leaves.

48. Cuscuta (Amarbel) is an example of:

1. Autotroph

2. Parasite

3. Saprotroph

4. Host

Ans: Correct option: b. Parasite 

Explanation: Cuscuta, commonly known as Dodder or Amarbel, is a genus of over 201 species of yellow, orange or red parasitic plants.

49. The plant which traps and feeds on insects is:

1. Cuscuta plant

2. China rose plant

3. Pitcher plant

4. Rose plant

Ans: Correct option: c. Pitcher plant 

Explanation: The plant which traps and feeds on insects is pitcher plant. 

50. When dilute iodine solution is poured over a decolourised green leaf, a blue-black colour is produced. This shows that the green leaf contains:

1. Glucose

2. Cellulose

3. Starch

4. sucrose

Ans: Correct option: c. Starch 

Explanation: When the dilute iodine solution is poured over a decolourised green leaf, a blue-black colour is produced. This shows that the green leaf contains starch.

51. The stem of one of the following plants can do photosynthesis. This plant is: 

1. Mushroom 

2. Croton 

3. Cuscuta 

4. Cactus 

Ans: Correct option: d. Cactus

Explanation: The stem's ability to photosynthesise after it has lost its leaves can promote plant carbon balance and prolong survival during drought. 

52. Which of the following plants has a heterotrophic mode of nutrition?

1. Money plant

2. Croton plant

3. Cuscuta plant

4. Alga plant

Ans: Correct option: c. Cuscuta

Explanation: They have suckers called suckers. These plants are parasitic and depend on other (host) plants for food. The sucking (sucking) roots of such plants help absorb nutrients such as water and food by penetrating the host plant's conductive blood vessels.

53. One of the following is not a parasite. This one is:

1. Lice

2. Leech

3. Alga

4. Cuscuta 

Ans: Correct option: c. Alga 

Explanation: Algae is an informal term that refers to a large and diverse group of photosynthetic eukaryotes.

54. Which of the following are not present in an animal cell?

1. Mitochondria 

2. Cytoplasm 

3. Chloroplast 

4. Large vacuole

1. A and B

2. B and C

3. A and C

4. C and D

Ans: Correct option: d. C and D

Explanation: Chloroplast and large vacuole are not present in an animal cell. 

55. Which of the following can make its own food?

1. Giraffe

2. Goat

3. Grass

4. Gorilla 

Ans: Correct option: c. Grass  

Explanation: Autotrophs are organisms that can produce their food using light, water, carbon dioxide, or other chemicals. Grass is an autotroph. 

56. One of the following is an autotroph. This one is:

1. Alligator

2. Algae

3. Antelope

4. Ant 

Ans: Correct option: b. Algae

Explanation: Algae is an informal term that refers to a large and diverse group of photosynthetic eukaryotes.

57. The process of photosynthesis converts solar energy into: 

1. Kinetic energy 

2. Chemical energy 

3. Potential energy 

4. Nuclear energy

Ans: Correct option: b. Chemical energy. 

Explanation: Plants also convert sunlight into other forms of energy. This is where plants convert light energy into chemical energy through a process known as photosynthesis.

58. Which of the following plant is an example of autotroph?

1. Mushroom 

2. Yeast

3. Bread mould

4. Mimosa  

Ans: Correct option: d. Mimosa

Explanation: Mimosa plant is an example of autotroph. 

59. Which one of the following is a heterotroph?

1. Mimosa 

2. Mushroom

3. Mango

4. Mangrove 

Ans: Correct option: b. Mushroom

Explanation: Mushroom is a heterotroph

60. Which of the following are saprophytes?

1. Mango 

2. Mushroom

3. Yeast 

4. Yak 

1. A and B

2. B and C

3. C and D

4. A and D

Ans: Correct option: b. B and C

Explanation: Mushroom and Yeast are saprophytes. Some bacteria survive by decomposing a variety of organic matter, including that from dead and decaying animals.

61. The green insectivorous plant trap insets, kill them and digest them to obtain mainly: 

1. Glucose

2. Starch

3. Nitrogen

4. Oxygen 

Ans: Correct option: c. Nitrogen

Explanation: To compensate for their lack of nitrogen, they catch insects and use their protein. Therefore, they are also known as insectivorous plants.

62. Which of the following show symbiosis?

1. Alga and fungus

2. Alga and fish

3. Rhizobium and pea plant

4. Rhizobium and money plant

1. A and B

2. B and C

3. A and C

4. C and D

Ans: Correct option: c. A and C

Explanation: Alga and fungus, and Rhizobium and pea plant show symbiosis. 

• Algae-fungi exhibit symbiotic relationships in lichens. Algae provide food for fungi, and fungi provide shelter for algae. 

• Pea plant has symbiotic nodules with Rhizobium leguminosarum sv. viciae (Rlv). In the field, it may uncover pea roots to a couple of well-matched Rlv strains.

63. The mineral needed by plants to make proteins is:

1. Neon 

2. Iodine 

3. Nitrogen 

4. Calcium 

Ans: Correct option: c. Nitrogen

Explanation: The mineral needed by plants to make proteins is nitrogen. 

64. The tubes (or pipes) which transport water and dissolved minerals from the soil to the leaves of a plant are called: 

1. Xylem 

2. Phloem

3. Epidermis 

4. Stomata 

Ans: Correct option: a. Xylem 

Explanation: The tubes (or pipes) that carry water and dissolved minerals from the soil to the leaves of plants are called xylem. Xylem, the vascular tissue of plants that transports water and dissolved minerals from the roots to the rest of the plant and also provides physical support.

65. Which of the following is not required for photosynthesis by the green leaves of a plant?

1. Carbondioxide 

2. Oxygen 

3. Sunlight 

4. Water 

Ans: Correct option: b. Oxygen

Explanation: Photosynthesis is the process by which plants synthesise food using carbon dioxide and water in the presence of sunlight and chlorophyll. Oxygen (O2) is released as a waste product during the process. Therefore, oxygen is not essential for the process of photosynthesis.

66. The simplest food produced during photosynthesis is:

1. Starch 

2. Cellulose 

3. Glucose 

4. Sucrose 

Ans: Correct option: c. Glucose 

Explanation: The simplest food that plants synthesise through photosynthesis is a simple carbohydrate called glucose. Glucose carbohydrates are made up of three elements: carbon, hydrogen and oxygen. Plants use the simple carbohydrate glucose to make many other foods, including starches, oils (or fats), proteins, and vitamins.

67. Which part of a plant is called its food factory?

1. Stem 

2. Roots 

3. Branches 

4. Leaves 

Ans: Correct option: d. Leaves

Explanation: Leaves are called the plant's food factories. 

68. In a cactus plant, food is made by:

1. Branches 

2. Roots 

3. Leaves 

4. Stem 

1. A and B

2. B and C

3. C and D

4. A and D

Ans: Correct option: A and D 

Explanation: Cacti, like other plants, produce food through photosynthesis. The difference from cacti, which makes food from another plant, is that cactus leaves are reduced to spines, so their stems contain chlorophyll, and photosynthesis takes place through the stems.

69. Which of the following gas is given out during photosynthesis?

1. Nitrogen 

2. Carbon dioxide 

3. Oxygen 

4. Water vapour

Ans: Correct option: b. Carbon dioxide

Explanation: Carbon dioxide is given out during photosynthesis. 

70. The carnivorous plants usually have one of the following specialised organs to catch their prey: 

1. Stems 

2. Branches 

3. Leaves 

4. Modified roots 

Ans: Correct option: c. Leaves

Explanation: The carnivorous plants have modified leaves to form trap organs, which have the unique ability to snap shut and catch flies and other small creatures that accidentally touch one of the trigger hair cells on the inner surface of the trap.

Questions Based on High Order Thinking Skills (HOTS)

71. The leaves of a plant combine a gas A taken from air and a liquid B taken from the soil in the presence of sunlight to make simple food C by the process called D. Some of the simple food C gets converted into a complex food E which is stored in the various parts of the plant including the leaves. 

1. What are 

1. Gas A 

2. Liquid B

Ans: Photosynthesis is the process in which plants absorb carbon dioxide (CO2) and water (H2O) from the air and soil. Water turns into oxygen and carbon dioxide turns into glucose. 

1. Gas A is carbon dioxide (CO2).

2. And the liquid B is water (H2O).

2. What are 

1. Food C

2. Food E

Ans: In photosynthesis process carbon dioxide turns into glucose. Glucose is converted to starch by a process called polymerisation. During polymerisation, several simple, soluble glucose molecules assemble into complex, insoluble starch molecules.

1. Food C is glucose.

2. Food E is starch.

3. Name the process D.

Ans: The process D is Photosynthesis. Photosynthesis is the process that plants and other organisms used to convert light energy into chemical energy, which is later released through cellular respiration to power the activity of the organism.

4. Which of the two foods, C or E, will give blue-black colour with dilute iodine solution?

Ans: The food E (starch) will give blue-black colour with dilute iodine solution. An iodine solution can be used to test for the presence of starch. When starch is present, iodine changes from brown to blue-black or purple.

5. Name the pigment present in leaves which helps in carrying out the food-making process D. 

Ans: Chlorophyll is the pigment present in leaves which helps in carrying out the food-making process. The role of chlorophyll in plants is to absorb light, usually sunlight. It transfers energy absorbed by light to two types of energy storage molecules. Through photosynthesis, plants use stored energy to convert carbon dioxide (obtained from the air) and water into glucose (a type of sugar).

72. The Plant X is found in abundance in desert areas which get meagre rainfall. The modified leaves of this plant can reduce the loss of water from this plant by transpiration. This plant has long roots which go deep into the soil to obtain water.

1. What could Plant X be?

Ans: The Plant X could be Cactus, because cactus is found in desert areas.

• The modified leaves of this plant can reduce the loss of water from this plant by transpiration. 

• Cactus roots reach deep into the ground to draw water

2. Which part/parts of this plant take part in photosynthesis?

Ans: In cacti, the leaves turn into spines. This is to prevent water loss through transpiration. Stems are green with chloroplasts. Therefore, the stems carry out photosynthesis in succulents.

3. How does the photosynthesis in this desert plant differ from those of ordinary plants found in a garden?

Ans: In terrestrial plants, photosynthesis takes place with the help of leaves containing chlorophyll, with the help of water and carbon dioxide in the presence of sunlight. 

• Desert plants turn their leaves into spines to prevent water loss. Therefore, CAM (Crassulaceae Acid Metabolic) photosynthesis takes place in desert plants.

4. What is the colour of the stem of this plant?

Ans: Cacti are perennials. Their stems are fleshy or juicy, cylindrical or flattened. The stems are green and carry out photosynthesis and usually perform this function in place of the leaves, although leaf mass is reduced or absent in most mature cacti.

73. The organs A of a tree have a large number of tiny pores called B on their surface. Each pore is surrounded by a pair of cells called C. The opening and closing of pores in A is controlled by C. The gas D present in air enters the organs A through pores B and utilised in food-making process E. The gas F produced during process E goes out through the same pores B. What are A, B, C, D, E and F?

Ans: Here A is leaves, B is stomata, C is guard cells, D is carbon dioxide, E is photosynthesis, and F is oxygen. 

• The surface of the leaves of plants has many small holes called stomata. 

• Carbon dioxide gas enters the leaves through stomata on the surface of the plant leaves. 

• A pair of guard cells surround each stoma. Guard cells control stomatal opening and closing. 

• When water flows into the guard cells, the cells swell and buckle, opening the pore. 

• When guard cells lose water, they shrink, straighten, and close their stomata.

74. The lamina of the leaf of a plant P is modified into a hollow tube. The leaf apex forms a kind of lid which can open or close the mouth of hollow tube. When an organism Q falls in the hollow tube, the lid closes automatically killing the organism. The walls of hollow tube secrete digestive juices which digest the complex substances R present in the body of the organism to form simpler substances S. These simpler substances are then absorbed by the walls of the hollow tube and used by the plant P.

1. What could the plant P be?

2. Name the organism Q.

3. What could the complex substances R be?

4. Name the simpler substances S.

5. What is the general name of plants like P?

Ans: 

1. P is Nepenthes, a carnivorous plant. Pitcher plants are a variety of carnivorous plants with modified leaves known as pitfalls.

2. The organism Q is an insect. When an organism Q (insect) falls in the tube, the lid closes automatically killing the organism.

3. R is chitin, the exoskeleton of insects, made from the monomer N-acetyl-glucosamine, a nitrogen-rich compound.

4. A simpler substance than S is N-acetyl-glucosamine, a modified monosaccharide.

5. These plants, commonly known as carnivorous plants, live in nitrogen-poor soils and receive nitrogen from insects.

75. Two different species of plants X and Y live together as if they are parts of the same plant Z. The Plant X is an autotroph whereas plant Y is a saprophyte. The plant Y holds the cells of X in its mat of web-like hyphae and supplies water and minerals to cells of Plant X. The Plant X makes food by photosynthesis and shares it with plant Y.

1. What could plant (i) X (ii) Y, and (iii) Z be?

2. Which of the two plants, X or Y, is green in colour?

3. What is the relationship exhibited by plants X and Y known as?

4. Give another example of this type of relationship.

Ans: 

1. Plant X is algae, Y is fungi and Z is lichen.

2. Plant X (algae) is green as the Plant X is an autotroph.

3. The relationship exhibited by plants X and Y known as symbiosis. The relationship between algae and fungi in lichens is symbiotic. Fungi provide protection and support to algae by helping absorb water. Conversely, algae provide food for fungi that lack chlorophyll pigment.

4. Symbiotic relationship between Rhizobium and leguminous plants. Legumes can form symbiotic relationships with nitrogen-fixing soil bacteria called rhizobia. This symbiosis results in the formation of nodules in plant roots where bacteria can convert atmospheric nitrogen into ammonia that plants can use.

Importance of Lakhmir Singh Class 7 Science Chapter 1 Nutrition In Plants Solutions

This is the first chapter of Class 7 Science Chapter 1 that explains organisms at the basic level. It then explains how plants acquire nutrition by defining the different cell organelles present in green plants.

It then introduces the different types of nutrition adopted by plants and animals. The photosynthetic process is explained in proper steps. Students will learn how this process is carried on in the green leaf cells in the presence of sunlight.

This chapter will then proceed to explain how nutrients are replenished in soil. There are different types of nutrients a plant needs to survive. It will explain the different modes of nutrition we can find in conventional and unconventional examples.

For instance, it has explained the symbiotic relationship between two organisms of different species. One of the best examples is the rhizobium where a bacterial species is in a symbiotic relationship with a multicellular leguminous plant for mutual benefits. All the other types of nutrition modes will be explained using proper examples. To make it easier, you can refer to Nutrition In Plants Class 7 Lakhmir Singh Solutions.

Benefits of Lakhmir Singh Solutions Science Class 7 Chapter 1

• The answer to all the exercise questions in this chapter will be discussed in these solutions. These answers have been formulated following the latest Class 7 Science syllabus for convenience.

• Following the answering format will enable students to grab the concepts well and to develop better answering skills for exams.

• Refer to the Nutrition In Plants worksheet notes and complete your revision before the exam faster. These notes have been designed to offer a simpler explanation of all the definitions, descriptions, and scientific principles related to nutrition in plants.

• The best way to clarify your doubts is by referring to these solutions. Hence, you will be able to prepare this chapter on your own and stay ahead of the competition.

• Use the Class 7 Science Chapter 1 Nutrition In Plants question answer section to evaluate your preparation level and learn which topics you need to study more in this chapter. In this way, you can improve your preparation level.

Download Class 7 Chapter 1 Nutrition In Plants Lakhmir Solutions PDF

Get the free PDF version of these solutions on Vedantu and refer to it for preparing this chapter. Once the chapter is completed, you can refer to these solutions to practice the exercise questions. Make your self-study sessions more productive by using these solutions at your convenience.