Ncert solutions science class 8 Solutions for Chapter 8 cell structure and functions

Muscle cells are branched. (T/F)

The basic living unit of an organism is an organ. (T/F)

Unicellular organisms have one-celled body. (T/F)

Amoeba has irregular shape. (T/F)

Q 1) Indicate whether the following statements are True (T) or False (F).

(a) Unicellular organisms have one-celled body. (T/F)

(b) Muscle cells are branched. (T/F)

(c) The basic living unit of an organism is an organ. (T/F)

(d) Amoeba has irregular shape. (T/F)

Choose the correct statement with respect to unicellular organisms:

(a) in unicellular organisms, tissues work in co-ordination to perform different functions.

(b) unicellular organisms do not require food.

(c) unicellular organisms respire and reproduce.

(d) all unicellular organisms move by cilia.

Indicate whether the following statements are True (T) or False (F).

(a) Unicellular organisms have one-celled body. (T/F)

(b) Muscle cells are branched. (T/F)

(c) The basic living unit of an organism is an organ. (T/F)

(d) Amoeba has irregular shape. (T/F)

Majority of cells cannot be seen directly with our naked eyes because:

(a) organisms are generally unicellular

(b) cells are microscopic

(c) cells are present only inside the body

(d) cells are grouped into tissues

Q 2) Make a sketch of the human nerve cell. What function do nerve cells perform?.

Make a sketch of the human nerve cell. What function do nerve cells perform?

Write short notes on the following.

(a) Cytoplasm

(b) Nucleus of a cell

Q 3) Write short notes on the following.

(a) Cytoplasm

(b) Nucleus of a cell

Read the different combinations of terms given below:

(a) cell wall, cell membrane, nucleus, plastid

(b) cell wall, nucleus, ribosome, chromosome

(c) cell membrane, mitochondria, ribosome, chromosome

(d) cell membrane, ribosome, mitochondria, chloroplast.

The correct combination of terms with reference to an animal cell is _____.

Q 4) Which part of the cell contains organelles?

Which one of the following term is not a part of the nucleus?

(a) ribosome

(c) chromosome

(b) nucleolus

(d) gene

Which part of the cell contains organelles?

Make sketches of animal and plant cells. State three differences between them.

A suitable term for the various components of cells is

(a) tissue

(b) cell organelles

(c) chromosomes

(d) genes

Q5) Make sketches of animal and plant cells. State three differences between them.

Q 6) State the difference between eukaryotes and prokaryotes.

The jelly-like fluid substance present in cells is called

(a) protoplasm

(b) chromosome

(c) chloroplast

(d) cytoplasm

Q 7) Where are chromosomes found in a cell? State their function.

Read the following pairs of examples of organisms:

(a) moss and sponge

(b) yeast and Amoeba

(c) bacteria and blue-green alga

(d) penicillium and Spirogyra

The pair that belongs to the group prokaryotes is_

Where are chromosomes found in a cell? State their function.

Q 8) ‘Cells are the basic structural units of living organisms’. Explain.

‘Cells are the basic structural units of living organisms’. Explain.

Read the following terms and select the pair that is related to the inheritance of characters.

(a) cell wall and cell membrane

(b) chromosome and mitochondria

(c) chloroplast and cell membrane

(d) chromosome and genes

Q 9) Explain why chloroplasts are found only in plant cells?

Explain why chloroplasts are found only in plant cells.

Choose the correct statement:

(a) Genes are located in the chromosomes.

(b) Cell is located in the nucleus.

(c) Chromosomes are located in the nucleolus.

(d) Cell membrane surrounds the nucleus.

Complete the crossword with the help of clues given below.

Across

1. This is necessary for photosynthesis.

3. Term for component present in the cytoplasm.

6. The living substance in the cell.

8. Units of inheritance present on the chromosomes.

Down

1. Green plastids.

2. Formed by collection of tissues.

4. It separates the contents of the cell from the surrounding medium.

5. Empty structure in the cytoplasm.

7. A group of cells.

Green colour of leaves is due to presence of the pigment_

(a) chlorophyll

(b) ribosomes

(c) mitochondira

(d) chloroplast

Q 10) Complete the crossword with the help of clues given below.

Across

1. This is necessary for photosynthesis.
2. Term for component present in the cytoplasm.
3. The living substance in the cell.
4. Units of inheritance present on the chromosomes.

Down

5. Green plastids.
6. Formed by collection of tissues.
7. It separates the contents of the cell from the surrounding medium.
8. Empty structure in the cytoplasm.
9. A group of cells.

The unit of measurement used for expressing dimension (size) of cells is:

(a) centimeter

(b) millimeter

(c) micrometer

(d) metre

The most important function of cell membrane is that it:

(a) controls the entry and exit of materials from cells.

(b) controls only the entry of materials into cells.

(c) controls only the exit of materials from cells.

(d) allows entry and exit of materials without any control.

Paheli accidentally placed her hand over a flame and immediately pulled it back. She felt the sensation of heat and reacted due to the action of

(a) blood cells

(b) skin surface

(c) nerve cells

(d) nucleus of cells

Of the following parts of a cell listed below, name the part that is common to plant cell, animal cell, and a bacterial cell.

(a) chloroplast

(b) cell wall

(c) cell membrane

(d) nucleus

The thread-like structures present in the nucleus are

(a) nucleolus

(b) chromosomes

(c) genes

(d) ribosomes

Which of the following feature will help you in distinguishing a plant cell from an animal cell?

(a) cell wall

(b) cell membrane

(c) mitochondria

(d) nucleus

Under a microscope, Paheli observes a cell that has a cell wall but no distinct nucleus. The cell that she observes is

(a) a plant cell

(b) an animal cell

(c) a nerve cell

(d) a bacterial cell

Cheek cells do not have _______

(a) cell membrane

(b) nucleus

(c) Golgi apparatus

(d) plastids

Which of the following statements are not true for eukaryotic cells?

(i) They do not have a nuclear membrane.

(ii) They have a well organized nucleus.

(iii) They have a nuclear membrane.

(iv) Blue-green algae are eukaryotic cells

Identify the correct statement about cells.

(a) All the cells have a nucleus.

(b) Cells of an organ have a similar structure.

(c) Cells of tissue have a similar structure.

(d) The shape of all types of cells is round.

The table given below has certain terms and four blank spaces named A, B, C, and D.

From the options given below choose the correct combination of terms.

(a) A-Pseudopodia; B-Respirations; C-Muscle cell; D-Branched

(b) A-Pseudopodia; B-Photosynthesis; C-Muscle cell; D-Branched

(c) A-Contractile vacuole; B-Photosynthesis; C-Blood cell; D-Spindle shaped

(d) A-Pseudopodia; B-Photosynthesis; C-Cheek cell; D-Spindle shaped from the options given below choose the correct combination of terms.

(a) A-Pseudopodia; B-Respirations; C-Muscle cell; D-Branched

(b) A-Pseudopodia; B-Photosynthesis; C-Muscle cell; D-Branched

(c) A-Contractile vacuole; B-Photosynthesis; C-Blood cell; D-Spindle shaped

(d) A-Pseudopodia; B-Photosynthesis; C-Cheek cell; D-Spindle shaped

In leaves, name the cell organelle and pigment that is responsible for green color.

The instrument used to observe cells is ________

We do not sense any pain when we clip our nails or cut our hair. Why?

In a cell, where are the genes located?

Amoeba and Paramecium belong to which category of organisms?

What are the functions of the cell wall in plant cells?

Is the following statement correct? If it is wrong, correct the statement Statement :

“Unicellular organisms do not respire, only multicellular organisms respire”

Match the terms given in column I with their functions given in column II and fill the blanks given below the table:

Observe the following diagram given as Fig.

Answer the following questions.

A. Does it represent a plant cell or an animal cell?

B. Does it represent a prokaryotic cell or a eukaryotic cell?

Label the parts A to E in the given as Fig. diagram.

Classify the following terms into cells, tissues, and organs and write in the tabular column given below.

RBC, WBC, Nerve cell, blood, muscle, blood vessels, brain, heart, hand

Read the following statements and write the appropriate term against each statement.

A. I control the functions of a cell. Who am I? ……………….

B. I am like a policeman. I do not allow anything and everything to get in and out of the cell. Who am I?

……………….

C. I transfer characters from parents to offsprings. Who am I? ……………….

Fill in the blanks with the terms given in the box below:

The outermost layer of plant cells is the (a) beneath which is the (b) . The term (c) refers to the jelly-like substance containing all the (d) . The (e) contains thread-like structures called (f) .

Cells consist of many organelles, yet we do not call any of these organelles as a structural and functional unit of living organisms. Explain.

Why do plant cells have an additional layer surrounding the cell membrane? What is this layer known as?

The size of the cells of an organism has no relation with the size of its body. Do you agree? Give reason for your answer.