Lakhmir Singh & Manjit Kaur: Cell Structure and Functions- 3 | Lakhmir Singh & Manjit Kaur Solutions: Class 8 Science PDF Download

Q.61. What are genes? Where are genes located?

Gene is a unit of inheritance in living organisms. It controls the transfer of a hereditary characteristic from parents to offspring. Genes are located on chromosomes.

Q.62. What is a plastid ? What is the name of green plastids present in plant cells? 

Plastids are major organelles found only in plant cells. The green coloured plastids present in plant cells, are called chloroplast. It contains photosynthetic pigment called chlorophyll which helps in the synthesis of food.

Q.63. What is the size of an ostrich egg? Is it a single cell or a group of cells? 

The size of an ostrich egg is 170 mm × 130 mm. It is the largest cell. It is a single cell called “fertilized egg cell” or “zygote”.

Q.64. What is the function of cell wall in a plant cell? 

Cell wall provides shape and rigidity to the plant cell. It also provides protection the cell.

Q.65. Name two cells which are found in animals and two which are found in plants. 

The cells which are found in animals are – Red blood cells (RBCs) and Muscle cells
The cells which are found in plants are – Xylem cells and phloem cells

Q.66.
(A) What is cytoplasm? What is its function?

Cytoplasm is a jelly-like substance present between the cell membrane and the nucleus. Cytoplasm contains many specialised cell organelles. Each of these organelles performs a specific function for the cell. Cytoplasm contains a number of minute living structure known as cell organelles. Each of these organelles performs a specific function for the cell.
Most of the chemical reactions which are necessary to keep cell alive take place in the cytoplasm.

(B) What is protoplasm? Name the elements which make up major part of protoplasm.

Cell without its cell membrane is called Protoplasm. The Cytoplasm and Nucleus taken together make up the protoplasm.

Q.67.
(A) What are unicellular organisms? Name two unicellular organisms.

The organisms made up of single cell are called unicellular organisms. Examples- Amoeba, Paramecium.

(B) What are multicellular organisms ? Name two multicellular organisms.

The organisms made up of many cells are called multicellular organisms. Examples- Animal and plant.

Q.68.
(A) Draw the general diagram of an animal cell and label it.

(B) Draw the general diagram of a plant cell and label it.

(C) Explain why, chloroplasts are found only in plant cells.

Chloroplasts are the green coloured plastids present in the cytoplasm of plant cells. They possess photosynthetic pigment called chlorophyll. Chlorophyll absorbs energy from the sunlight during the process of photosynthesis. In the process of photosynthesis, green plants make their own food in the presence of sunlight and chlorophyll with the help of inorganic substances like carbon dioxide and water. Thus, chloroplast help in the synthesis of food by green plants.

Q.69.
(A) An Ameoba cell can change its shape and a white blood cell in human blood can also changing its shapes. What is the difference between an Amoeba cell and a white blood cell?

An Ameoba cell can change its shape and a white blood cell in human blood can also changing its shapes. The difference between an Amoeba cell and a white blood cell is that the Amoeba cell is a full-fledged organism which is capable of independent existence. While white blood cell is only a cell of human blood which is not a full-fledged organism and hence cannot exist independently. White blood cells can exist only inside the blood.

(B) Out of Amoeba cell and white blood cell, which one is

• eukaryotic cell, and
• prokaryotic cell?

Amoeba cell and White Blood Cell both are eukaryotic cell because they have well defined nucleus with a nuclear membrane.

Q.70. 
(A) State three difference between a plant cell and animal cell?

Differences between a plant cell and animal cell:

(B) Which of the following are prokaryotic cells and which are eukaryotic cells?
Amoeba cell, Bacterium cell, Human cheek cell, Blue-green algae cell, onion peel cell.

Q.71. The organelles which provide energy for all activities of a cell are:
(a) Chloroplasts
(b) Mitrochondria
(c) Golgi bodies
(d) Ribosomes

Correct Answer is Option (b)
Mitochondria is the site of cellular respiration or oxidation of food in a cell. It uses glucose and oxygen to produce energy. Hence, it is knowns as “Powerhouse of the cell”.

Q.72. In a living cell, chromatin is present in:
(a) Cytoplasm
(b) Chloroplasts
(c) Nucleus
(d) Vacuole

Correct Answer is Option (a)
Chromatin material is a tangled fibrous mass. The chromatin material condenses to form chromosomes during cell division.

Q.73. The cell wall in onion peel cell is made of:
(a) Starch
(b) Gelatin
(c) Cellulose
(d) Cell sap

Correct Answer is Option (c)
The cell wall in onion peel cell is made of cellulose.

Q.74. The group of similar cell which work together to perform a particular functions is called:
(a) Organ
(b) Organelle
(c) Organisms
(d) Tissue

Correct Answer is Option (d)
The group of similar cells which work together to perform a particular function is called tissue.

Q.75. A long and branched animal cell is:
(a) Muscle cell
(b) Epithelial cell
(c) Nerve cell
(d) Cartilage cell

Correct Answer is Option (c)
Nerve cells (neurons) are long, branched and have thread-like projections so that they can connect other nerves cells and transmit messages over long distance.

Q.76. Which of the following is not a unicellular organism?
(a) Amoeba
(b) Yak
(c) Yeast
(d) Rhizobium

Correct Answer is Option (a)
Amoeba, yeast and rhizobium are examples of unicellular organisms while Yak is an example of multicellular organisms.

Q.77. Which of the following organelle is not found in the root cells of a plant?
(a) Nucleus
(b) Vacuole
(c) Mitochondria
(d) Chloroplasts

Correct Answer is Option (d)
Chloroplasts are found only in those plant cells which carry out photosynthesis like the cells in green leaves. So, chloroplasts are not found in the root cells of a plant.

Q.78. The part of a cell which plays a role in inheritance is:
(a) Nucleus
(b) Cytoplasm
(c) Plasma membrane
(d) Mitochondria

Correct Answer is Option (b)
Nucleus contains thread-like structures called chromosomes. These carry genes and help in inheritance or transfer of characters from the parents to the offspring.

Q.79. The basic similarity among all the living organisms is that they are made up of :
(a) Tissue
(b) Organs
(c) Cells
(d) Organ systems

Correct Answer is Option (c)
The basic similarity among all the living organisms is that they are made up of cells. Cell is the structural and functional unit of life.

Q.80. The structural and functional unit of life called cell was discovered by :
(a) Robert Boyle
(b) Charles Darwin
(c) Robert Koch
(d) Robert Hooke

Correct Answer is Option (d)
The structural and functional unit of life called cell was discovered by Robert Hooke.

Q.81. Which of the following cell does not have a nucleus?
(a) White blood cell
(b) Red blood cell
(c) Nerve cell
(d) Muscle cell

Correct Answer is Option (b)
Red blood cell does not have a nucleus.

Q.82. The parts which are not present in an animal cell are:
(A) Cell membrane
(B) Chloroplast
(C) Cell wall
(D) Mitochondria
(a) A and B
(b) B and C
(c) A and D
(d) B and D

Correct Answer is Option (b)

Q.83. All the living matter in a cell is called :
(a) Endoplasm
(b) Protoplasm
(c) Cytoplasm
(d) Cell sap

Correct Answer is Option (b)
The entire content of a living cell is known as protoplasm. It includes the cytoplasm and the nucleus. Protoplasm is called the living substance of the cell.

Q.84. Which of the following is a plant cell?
(a) Cartilage cell
(b) Neuron
(c) Epidermal cell
(d) Epithelial cell

Correct Answer is Option (c)
Epidermal cell is a plant cell while cartilage cell, neuron and epithelial cell are animal cells.

Q.85. The egg cell measuring about 17 cm × 13 cm is most likely that of:
(a) Hummingbird
(b) Hen
(c) Elephant
(d) Ostrich

Correct Answer is Option (d)
The largest cell measuring 170 mm ×130 mm, is the egg of an ostrich.

Q.86. Which of the following have cell walls?
(A) Epidermal cell
(B) Epithelial cell
(C) Mesophyll cell
(D) Liver cell
(a) A and B 
(b) B and C 
(c) A and C 
(d) B and D

Correct Answer is Option (c)
Cell wall is a characteristics of plant cell only and absent in animal cell. It is an outer, rigid, protective and supportive covering of plant cells. The cell wall lies outside of the plasma membrane. Epidermal cell and mesophyll cell are examples of plant cells. Thus, they have cell wall.

Q.87. Which of the following are prokaryotes?
(a) Protozoa
(b) Blue – green algae
(c) Fungi
(d) Bacteria

Correct Answer is Option (d)
Organisms which do not have true nucleus are called prokaryotes. Bacteria and blue green algae are examples of prokaryotes.

Q.88. Which of the following human system includes oesophagus?
(a) Respiratory system
(b) Circulatory system
(c) Digestive system
(d) Reproductive system

Correct Answer is Option (c)
Oesophagus is a part of human digestive system. It is a muscular tube which connects the pharynx to the stomach. It is also known as food pipe.

Q.89. Which of the following cells can change their shape?
(A) White blood cell
(B) Amoeba cell
(C) Red blood cell
(D) Euglena cell
(a) A and B
(b) B and C
(c) A and D
(d) B and D

Correct Answer is Option (a)
An amoeba cell and white blood cell present in human blood can change their shape.

Q.90. The non-living part of a tomato cell is its:
(a) Cell membrane
(b) Nucleus
(c) Chloroplasts
(d) Cell wall

Correct Answer is Option (d)
The non-living part of a tomato cell is its cell wall. Cell wall is the outer most covering of a plant cell. It is a non-living and rigid.

Q.91. The part of P and Q are present only in plant cells, and they are not present in animal cells. The part P contains a green pigment called R whereas part Q is made of a tough material S. The part P takes part in the food making process whereas part Q gives shape and support to the plant cell.
(a) What is (i) P, and (ii) Q?
(b) What is (i) R, and (ii) S?

(a) (i) The part P is Chloroplasts Chloroplasts are the food producers in plant cells and they are not present in animal cells because animal cells do not make their own food.
(ii) The part Q is Cell wall The cell wall is absent in the animal cells because they don’t need cell walls. The main purpose of a cell wall is to provide stability and stiffness to the cell. And it is made up of cellulose.
(b) (i) The part R is Chlorophyll Chlorophyll is the green pigment present in the leaves.
(ii) The part S is Cellulose Cellulose is a fiber and wood, cotton, etc. all contain cellulose.

Q.92. A, B, C and D are the basic part of all the cells. The part A contains thread- like structures called E which transfer the characteristic from parents to their off springs. The part B uses glucose and oxygen to produce energy whereas part C controls the movement of substance into the cell. The part D is a transparent, jelly-like material. What could A, B, C, D and E be?

A is nucleus ; B is mitochondria; C is cell membrane ; D is cytoplasm; and E is chromosomes.

Q.93. X and Y are the two types of cells. The cells X have a well organized nucleus which is separated from the cytoplasm by the nuclear membrane On the other hand, cells Y do not have a real nucleus, their nuclear material is in direct contact with the cytoplasm.
(a) what type of cells are (i) X, and (ii) Y?
(b) Give one example each of cells like (i) X, and (ii) Y?

(a) (i) Eukaryotic cell (ii) Prokaryotic cell
(b) (i) Amoeba cell (ii) Bacterium cell

Q.94. The cytoplasm of the cells of a tomato plant contains organelles X having different pigments which impart different colours to the leaves of tomato plants and its fruits.
(a) What is the general name of the organelles X?
(b) What is the (i) name (ii) colour, and (iii) function, of organelles X present in the leaves of Tomato plant?
(c) What is the colour of organells X which are present in the ripe fruits of tomato plant?

(a) The general name of the organelles X is plastids.
(b) (i) Chloroplasts (ii) green (iii) Chloroplasts (X) help in the synthesis of food by the process of photosynthesis.
(c) The colour of organells X which are present in the ripe fruits of tomato plant is red.

Q.95. Cell make up A; A make up B; B make up C, and finally C make up an organism. What are A, B, and C ?

A is tissue; B is organ; and C is organ system.