Question 1 ( 1.0 marks)
What is the function of ribosomes?
Solution:
Ribosomes act as the site for protein synthesis.
Question 2 ( 1.0 marks)
Name the cell organelle in which chromosomes are found.
Solution:
Nucleus
Question 3 ( 1.0 marks)
Name the three types of meristematic tissues.
Solution:
Apical meristem, intercalary meristem and lateral meristem
Question 4 ( 1.0 marks)
Where is the apical meristem found?
Solution:
Apical meristem is present at the growing tips of stems and roots.
Question 5 ( 1.0 marks)
Which is the second largest phylum of kingdom animalia?
Solution:
Phylum mollusca
Question 6 ( 1.0 marks)
Which mode of respiration is found in adult amphibians?
Solution:
Adult amphibians respire through lungs and skin.
Question 7 ( 1.0 marks)
Fill in the blanks.
Plants that produce naked embryos are called __________, while those that produce seeds are called __________.
Solution:
Plants that produce naked embryos are called cryptogams, while those that produce seeds are called phanerogams.
Question 8 ( 1.0 marks)
What is the name of the causal organisms of typhoid and rabies?
Solution:
Causal organism of typhoid − Bacteria
Causal organism of rabies − Virus
Question 9 ( 1.0 marks)
Define antigen.
Solution:
Antigen is any foreign substance that invades our body, e.g., microorganisms.
Question 10 ( 1.0 marks)
Who invented vaccination for small pox?
Solution:
Edward Jenner
Question 11 ( 1.0 marks)
Name any two transgenic plants.
Solution:
Bt cotton and Flavr savr tomato
Question 12 ( 1.0 marks)
Name any two common weeds.
Solution:
Xanthium and Parthenium
Question 13 ( 2.0 marks)
Name the components of nucleus and write one function of each.
Solution:
Components of nucleus:
(i) Nuclear membrane − It is a double membrane with pores that allow the movement of specific substances in and out of the nucleus.
(ii) Nucleoplasm − It is a dense fluid in which chromatin and nucleolus are present.
(a) Chromatin − It is an entangled mass of thread-like structure containing the genetic material.
(b) Nucleolus − It is the site for ribosome formation.
Question 14 ( 2.0 marks)
List the important functions of parenchyma.
Solution:
Important functions of parenchyma:
(i) To store food and water
(ii) To provide support to the stem and herbaceous plants, and to maintain the shape and firmness of the plant body
(iii) Chlorenchyma carries out photosynthesis, and aerenchyma provides buoyancy to aquatic plants to keep them afloat.
(iv) Intracellular air spaces in parenchyma permit gaseous exchange.
Question 15 ( 2.0 marks)
Name two types of protective tissues found in plants and give two functions of each.
Solution:
Two types of protective tissues are cork and epidermis.
Functions of cork:
(i) To prevent water loss by evaporation
(ii) To protect the plant against mechanical injury, temperature extremes, etc.
Functions of epidermis:
(i) It protects the plants against mechanical injury.
(ii) The stomata present on it help in gaseous exchange and transpiration.
Question 16 ( 2.0 marks)
Define the following.
(i) Classification
(ii) Enterocoelom
Solution:
(i) Classification refers to the identification, naming and grouping of organisms into a formal system based on similarities of internal and external structures or evolutionary history.
(ii) Enterocoelom refers to the true body cavity formed from pouches that are pinched off from the endoderm.
Question 17 ( 2.0 marks)
How do mammals differ from the aves?
Solution:
Mammals differ from the aves because of the presence of the following features.
(i) Milk-producing glands (mammary glands) to nourish their young ones
(ii) Two pairs of limbs for walking, running and flying
(iii) Hair and sweat glands on the skin
Question 18 ( 2.0 marks)
Complete the table.
Solution:
Question 19 ( 2.0 marks)
How does community affect the health of an individual?
Solution:
Various factors affecting a community also affect the individual who is a part of that community. These are:
(i) Location of the community − Climate affects the health of a community. For example, in tropical areas, the climate is hot and humid, which promotes the growth of parasites. As a result, diseases are more prevalent.
(ii) Size of the community − Due to high population density, a larger population will have more diseases. However, at the same time, it will have more health professionals to deal with the diseases.
(iii) Development and economy of the community will also affect the health of the community.
Question 20 ( 2.0 marks)
Define the following.
(i) Mixed cropping
(ii) Intercropping
Solution:
(i) Mixed cropping − The practice of growing two or more crops simultaneously on the same land such that the product or waste material of one crop helps in the growth of another crop
(ii) Intercropping − The technique of growing crops with different nutritional requirements (e.g., soyabean and maize) in alternate rows, in a definite pattern, to ensure maximum utilisation of nutrients.
Question 21 ( 3.0 marks)
Which cell organelle is known as the “power house of a cell”? Explain why it is called so.
Solution:
Mitochondrion is called the powerhouse of a cell. This is because most of reactions of cellular respiration occur in the mitochondria. ATPs (Adenosine triphosphate), which are the energy currency of cells, are produced as a result of these reactions. The body uses the energy stored in ATP for making new compounds, and for performing mechanical work.
Question 22 ( 3.0 marks)
List the components of phloem. Mention one function of each component.
Solution:
Phloem is made up of four types of cells. These are −
(i) Sieve tubes
(ii) Companion cells
(iii) Phloem parenchyma
(iv) Phloem fibres
Sieve tube − Transport food materials
Companion cells − Carry out the cellular functions of the sieve tube elements
Phloem parenchyma − Responsible for the storage of food
Phloem fibres − Provide mechanical strength to the cells
Question 23 ( 3.0 marks)
What do you understand by body symmetry? Give two examples each of animals that are:
(i) Radially symmetrical
(ii) Bilaterally symmetrical
Solution:
Body symmetry is the balanced distribution of duplicate body parts.
If the body of an animal can be divided into two equal parts by any plane, it is said to be symmetrical.
(i) Animals showing radial symmetry − Hydra and sea anemone
(ii) Animals showing bilateral symmetry − Human beings and prawn
Question 24 ( 3.0 marks)
What are antibiotics? How do they work? How does penicillin act as an effective antibiotic to control bacterial parasites?
Solution:
Antibiotic is a medicine that kills a microorganism by blocking its vital biochemical pathways.
Microorganisms have certain biochemical pathways which are needed for their survival; for example, respiration and enzyme synthesis. Antibiotics bind with the precursors needed for these pathways, and block them. In the absence of essential life processes, the microorganisms are killed.
Penicillin blocks the cell-wall formation in bacterium. As a result, bacterium is killed. Hence, it acts as an effective antibiotic to control bacterial parasites.
Question 25 ( 5.0 marks)
Answer the following questions.
(i) Write a short note on treatment of diseases.
(ii) What are air-borne diseases? Explain how these diseases can be prevented.
Solution:
(i) Once a body becomes diseased, it needs to be treated so that the body can regain its strength and efficiency.
A disease can be treated in two ways −
(a) By reducing the effect of the disease: In this, the side effects or symptoms of the disease are reduced. This includes consuming medicines to bring down fever, reduce pain, etc., or taking rest to save energy so that the body can focus on healing.
(b) By killing the cause of the disease: It includes consuming a specific medicine particular to the disease-causing microorganism. These medicines block the vital biochemical pathways of the microbes (such as respiration and enzyme synthesis). This kills the microorganisms.
(ii) Air-borne diseases are the ones that are transmitted when disease-causing microorganisms are expelled into the air while coughing, sneezing, talking, etc. These microorganisms travel through dust particles or water droplets in air to reach the other individuals.
Some common air-borne diseases are common cold, tuberculosis, swine flu, pneumonia, etc.
Prevention of air-borne diseases:
(a) By staying away from the diseased person
(b) By wearing a mask while contacting the sick person
(c) By covering one’s mouth or nose while coughing or sneezing to prevent the spread of infection.
Question 26 ( 5.0 marks)
Answer the following questions.
(i) What are the main functions of the plasma membrane?
(ii) What are the main functions of the cell wall?
(iii) Differentiate between the plasma membrane and the cell wall.
Solution:
(i) Functions of the plasma membrane:
(a) It gives shape and support to the cell.
(b) It acts as a mechanical barrier to protect the internal contents of the cell.
(c) It separates the contents of the cell from its surrounding medium.
(d) It performs physical activities such as diffusion and osmosis.
(ii) Functions of the cell wall:
(a) It provides structural strength to the plant cells.
(b) It enables the plant cells to withstand external hypotonic media without bursting.
(c) It gives shape to the cells.
Due to the presence of the cell wall, plant cells can efficiently withstand the surrounding media as compared to animal cells.
(iii) Difference between the cell wall and the plasma membrane:
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