Free The Fundamental Unit of Life 03 Practice Test - 9th Grade 

Question 1

Why is cell called the fundamental unit of life?

A. Cells cannot be broken into smaller components.
B.

Cells are the smallest unit which is said to be living.

C.

Cells are made up of water.

D.

Cells are found in all the organisms.

SOLUTION

Solution : B

Cells are the basic structural and functional unit of life as they are the smallest unit which can be called living. One complete cell is capable of performing all the physiological activities. Cells combine to form tissues, which are a collection of cells performing a similar function. Tissues combine to form organs and organs combine to form an organ system. Many organ systems together form an entire individual or organism. 

Question 2

Statement 1: All cells arise from pre-existing cells.
Statement 2: All cells have a cell wall.

A. Both the statements are correct.
B. Only statement 1 is correct.
C. Only statement 2 is correct.
D. Both the statements are incorrect.

SOLUTION

Solution : B

The cell theory was proposed by Matthias Schleiden (1838) and Theodor Schwann (1839), after studying plants and animal cells independently. It states that:
  • All living organisms are made up of cells.
  • Cells are the smallest units in a living organism that can perform all the functions of life.
  • Rudolf Virchow in 1858 said "Omnis cellula-e-cellula", which means that all cells arise from the pre-existing cells only.
Cell wall is a rigid outer layer which is present in bacterial, fungal and plant cells, but not present in animal cells.

Question 3

Plasma membrane is mainly composed of:

A. Lipids
B. Chitin
C. Cellulose
D. Proteins

SOLUTION

Solution : A and D

Plasma membrane is a selectively permeable membrane. It covers the cytoplasm. It is made up of a phospholipid bilayer with protein molecules embedded in it. It also consists of carbohydrates and water. The ratio of proteins to lipids varies in different membranes. 

Question 4

The functional segments of DNA are genes.

A.

True

B.

False

SOLUTION

Solution : A

Genes are the functional segments of DNA. They are the smallest units of DNA which determines a particular trait of an organism.
The main function of DNA at a molecular level, is to signal the ribosomes to form proteins.

Question 5

Which of the following statements is/are true?

A. Plant cells lack cell wall.
B. Animal cells have centrioles.
C. Plant cells have a large vacuole.
D. Animal cells do not have plastids.

SOLUTION

Solution : B, C, and D

  • Plant cells are characterised by the presence of a rigid cell wall made up of cellulose, whereas animal cells do not contain cell wall. 
  • Centrioles are barrel-shaped organelles found in the cells of animals and protists. They are involved in cell division. They are absent in higher plants such as gymnosperms and angiosperms.
  • In plant cells only one large prominent vacuole is present. In animal cells on the other hand, vacuoles are smaller in size and more in number.
  • Animal cells do not contain plastids like chloroplasts (which contains chlorophyll), chromoplasts (coloured plastids) and leucoplasts (colourless plastids).

Question 6

Viruses lack cellular machinery until they enter a living host and multiply.

A.

True 

B.

False

SOLUTION

Solution : A

Viruses do not have a cellular machinery. They behave as non-living particles outside their host cell but start reproducing and multiplying once they enter their host.
Hence, they form the bridge between living and non-living.

Question 7

Where are the proteins synthesised inside the cell?

A.

Lysosomes

B.

Golgi apparatus

C.

Ribosomes

D.

Nucleus

SOLUTION

Solution : C

Ribosomes are small structures which are either found in a free state, floating in the cytoplasm or attached to the rough ER, giving it a rough appearance. These ribosomes, which are present in both prokaryotic and eukaryotric cells, are the site of protein synthesis.

Question 8

Why do different cells have different shapes?

A.

Cells get modified according to the function they perform.

B. Cells choose random shape for themselves.
C. Cells attain different shapes in response to stress.
D. Different cell shapes are a part of the evolution in the organism.

SOLUTION

Solution : A

Cells modify themselves according to the function they perform. Therefore, different cells have different shapes. For example, nerve cells have long processes called axons, as they have to carry information to long distances.

Question 9

Leucoplasts are present in___.

A. plant cells only
B. both plant and animal cells
C. animal cells only
D. neither plant nor animal cell

SOLUTION

Solution : A

Leucoplasts are the non-pigmented organelles which are colorless. They are usually found in most of the non-photosynthetic parts of the plant like roots. They act as a storage shed for starches, lipids, and proteins depending on the needs of plant.

Question 10

In a non-dividing cell, DNA is present as a mass of thread-like structures known as _______ .

A. ribosomes
B. chromatin
C. cytoplasm
D. chromosome

SOLUTION

Solution : B

In a cell which is not dividing, DNA is present as part of chromatin fibres/material. These are called chromatin because they get coloured when they are stained. This chromatin material is visible as an entangled mass of thread-like structures. Whenever the cell is about to divide, the chromatin material gets condensed and organised into chromosomes.
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