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Chapter 3

Cell — The Structure and Functions

Class 6 - Concise Biology Selina


Multiple Choice Questions

Question 1

Identify the part which contains pigment:

  1. Cell membrane
  2. Plastid
  3. Centrosome
  4. Cell wall

Answer

Plastid

Reason — Plastids contain pigments.

Question 2

The organelle that controls all activities in a cell:

  1. Nucleus
  2. Vacuole
  3. Plastid
  4. Cytoplasm

Answer

Nucleus

Reason — Nucleus is the most important part of the cell. It regulates and coordinates various life processes of the cell.

Question 3

A cell that is spherical in shape is:

  1. White blood cell
  2. Nerve cell
  3. Red blood cell
  4. Amoeba

Answer

Red blood cell

Reason — Red blood cell are spherical in shape and this specific shape enables them to hold more oxygen and easily flow through vessels and capillaries.

Question 4

The vacuole contains:

  1. Water
  2. Cell sap
  3. Salts
  4. Food

Answer

Cell sap

Reason — Vacuoles are filled with water and various substances in solution from called cell sap.

Short Answer Questions

Question 1

Name the scientist who invented the first microscope?

Answer

The Scientist who invented the first microscope is Antonie Van Leeuwenhoek.

Question 2

Who coined the term "cell"?

Answer

Robert Hooke coined the term "cell".

Question 3

Briefly describe the three essential parts of the cell.

Answer

The three essentials parts of the cell are Cell membrane, Cytoplasm and Nucleus.

  1. Cell membrane — Each cell is surrounded by a membrane which is called cell membrane. It is a living structure that is very thin, delicate and flexible. It has fine pores in it, through which only certain substances can pass in and out while others cannot. Therefore, the cell membrane is called selectively permeable.
  2. Cytoplasm — The cytoplasm is a semi-liquid, colourless, and translucent substance. It is found between the nucleus and the cell membrane.
  3. Nucleus — Nucleus is a small spherical maas mostly located towards the centre of the cytoplasm. It is the most important part of the cell. It regulates and coordinate various life processes of the cell. It plays an important role during cell division.

Question 4

The cell membrane is called selectively permeable? Why?

Answer

The cell membrane is called selectively permeable because it allows only entry of specific substances, while holding back the others.

Question 5(a)

State the difference between Nucleus and Nucleolus.

Answer

Difference between Nucleus and Nucleolus:

NucleusNucleolus
Nucleus is a small spherical mass mostly located towards the centre of the cytoplasm.Nucleolus is a small darker body, which is present in the nucleoplasm inside the nucleus.
Nucleus regulates and coordinates various life processes of the cell.Nucleolus helps in protein synthesis and production of the ribosome in the cells.

Question 5(b)

State the difference between Cytoplasm and Protoplasm.

Answer

Difference between Cytoplasm and Protoplasm:

CytoplasmProtoplasm
The cytoplasm is a semi-liquid, colourless and translucent substance of the cell.Protoplasm is a jelly-like living substance of the cell.
Cytoplasm is all the contents inside the cell membrane excluding the nucleus.Protoplasm includes cytoplasm, plus, the nucleus of the cell.

Question 5(c)

State the difference between Cell Wall and Cell Membrane.

Answer

Difference between Cell Wall and Cell Membrane:

Cell WallCell Membrane
Cell Wall is found in the plant cell.Cell Membrane is found in both the plant cell and animal cell.
Cell Wall is a non living structure.Cell Membrane is a living structure.
Cell Wall is freely permeable, allowing substances in solution to enter and leave the cell without any hindrance.Cell Membrane is selectively permeable, allowing only certain molecules in solution to enter and leave the cell.

Question 6

List the major differences between a plant cell and an animal cell?

Answer

Difference between plant cell and animal cell:

Plant CellAnimal Cell
Plant cell has a definite cell wall.Animal cell has no cell wall.
Cytoplasm not so dense. Only a thin layer of cytoplasm.Cytoplasm denser and more granular. It fills almost the entire cell.
Plastid are present.Plastid are not present.
Vacuoles prominent, fewer in number and concerned with storage of water and nutrients.Vacuoles are small, numerous and concerned with excretion or secretion.

Question 7

Briefly discuss the importance of the chromosomes in an organism?

Answer

The Nucleoplasm of the nucleus contains chromosomes. Chromosomes contain units called Genes. These genes are responsible for transmitting characteristics from parents to offsprings. Thus, the chromosomes are extremely important for an organism.

Question 8

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

pigments, wall, pre-existing , cell, vacuoles

  1. The ............... is the structural unit of all living things
  2. All cells arise from ............... cells.
  3. Animal cells have no cell ............... .
  4. Plastids contain ............... .
  5. ............... are filled with water and dissolved substance.

Answer

  1. The cell is the structural unit of all living things.
  2. All cells arise from pre-existing cells.
  3. Animals cells have no cell wall.
  4. Plastids contain pigment.
  5. Vacuoles are filled with water and dissolved substances.

Question 9

Try to finds the names of four cell organelles hidden in this maze. (Hint: The hidden words can appear horizontally or vertically; forward or backward or even mixed up). Write them in the lines provided. For example: "NUCLEUS" in the last row, seven backward letters.

Try to finds the names of four cell organelles hidden in this maze. (Hint: The hidden words can appear horizontally or vertically; forward or backward or even mixed up). Write them in the lines provided. For example: NUCLEUS in the last row, seven backward letters. Cell - The Structure and Functions, Concise Biology Solutions ICSE Class 6.

Answer

The hidden four cell organelles are:

  1. Vacuole
  2. Leucoplast
  3. Chromoplast
  4. Plastid

The solved maze is shown below:

Try to finds the names of four cell organelles hidden in this maze. (Hint: The hidden words can appear horizontally or vertically; forward or backward or even mixed up). Write them in the lines provided. For example: NUCLEUS in the last row, seven backward letters. Cell - The Structure and Functions, Concise Biology Solutions ICSE Class 6.

Long Answer Questions

Question 1

Briefly describe the structure of nucleus and mention its any two function.

Answer

Nucleus is a small spherical mass mostly located towards the centre of the cytoplasm. Nucleus has the following parts:

  1. A delicate, porous nuclear membrane which encloses a relatively dense Nucleoplasm.
  2. Inside the nucleoplasm the small darker body Nucleolus is present. The nucleoplasm contains chromosomes.

Below diagram shows the structure of the Nucleus:

Briefly describe the structure of nucleus and mention its any two function. Cell - The Structure and Functions, Concise Biology Solutions ICSE Class 6.

The two functions of nucleus are:

  1. It regulates and coordinates various life processes of the cell.
  2. It plays an important role in cell division.

Question 2

Name the scientist who coined the term "cell". How many lenses did he use in his microscope? What did he observe under his microscope?

Answer

Robert Hooke is the scientist who coined the term "cell". He used two lenses in his microscope. Under his microscope, he examined a very thin slice of a dead cork (the bark of the trees) and observed a cluster of box-like cubicles piled up together.

Question 3

Name the three essential parts of the cell. Briefly describe the structure of cell membrane.

Answer

The three essential parts of the cell are:

  1. Cell membrane
  2. Cytoplasm
  3. Nucleus

Structure of Cell Membrane:

  1. The each cell is surrounded by a cell membrane, also called plasma membrane.
  2. It is very thin, delicate and flexible.
  3. It is a living structure present in both animal and plant cells.
  4. It has fine pores in it, through which only certain substances can pass in and out, while others cannot. Therefore, the cell membrane is called selectively permeable.
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