Class 8 Science Chapter 8 MCQ

A cell is the smallest and basic unit of life which has definite structure and performs a specific function. Most of them cannot be seen with naked eyes because they are microscopic (i.e., very-very small).

Here, all the statements are correct. Hence, your answer will be 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

The correct combination of terms with reference to an animal cell is cell membrane, mitochondria, ribosome and chromosome. An animal cell does not have a cell wall, plastic and chloroplast, but these are present in plant cells.

Bacteria Mycoplasma is the smallest cell. The size of this cell is 0.0001 mm or 0.1 micrometre.

Cytoplasm is the transparent jelly like fluid which fills the cell between nucleus and cell membrane. Most of the chemical reactions which keep the cell alive takes place here. i)Protoplasm is the living substance of the cell. It includes the cytoplasm and nucleus. ii)Chromoplasts are coloured plastids present in plant cell. iii)Chromosomes are thread like structures present in nucleus.

Bacteria and blue-green algae are examples of prokaryotes. These organisms consist of prokaryotic cell (no nuclear membrane, no well-defined nucleus and no other cell organelles).

Genes are the unit of inheritance located in the chromosomes. The other statements are incorrect and their correct from are as: i)Nucleus is located in the cell. ii)Chromosomes are located in the nucleus. iii)Cell membrane surrounds the cell and nuclear membrane surrounds the nucleus.

The pigment chlorophyll present in the chloroplasts, which is responsible for green colour of leaves. It can absorb solar energy for photosynthesis.

Here, all the statements are correct. Hence, your answer will be option [D].

Nucleus contains thread-like structures called chromosomes. These carry genes and help in inheritance or transfer of characters from the parents to the offspring.

Red blood cell does not have a nucleus.

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.

Micrometre is the unit of measurement used for expressing dimension of cell.

Nails and hair are made up of dead cell. They do not have protoplasm and nerve cells, hence one does not feel pain, when they are clipped or cut.

The cell membrane controls the entry (movement into the cell) and exit (movement out of the cell) of materials. It also protects and gives shape to the cell.

Nerve cells have a special shape-long and branched (with projections) to receive and transmit message between the brain and the other body parts. Thus, they help to feel sensations and in responding to them.

Here, all the statements are correct. Hence, your answer will be option [D].

A unicellular organism consists of a single cell that is capable of performing all the functions. The other statements in true form are: i)Cells cannot be seen easily with naked eyes. ii)Insect’s egg is a single cell. iii)The shape and size of a cell are different in multicellular organisms.

Here, all the statements are correct. Hence, your answer will be option [D].

A cell wall is the distinguishing feature between a plant cell and animal cell. It is thick wall made up of cellulose around cell membrane that exclusively present only in plant cell.

The cell observed by Paheli is a bacterial cell. It is a prokaryotic cell that has a cell wall (like plants) but no distinct nucleus. A plant cell has a cell wall and a well-defined nucleus, whereas in an animal cell, the former is not present. A nerve cell is an animal cell that is long and branched to function as transmitter between brain and other parts.

Cheek cells are animal cells. So, there will be no plastids. All other cell organelles such as the nucleus, GA, ribosomes, etc., are enclosed in the cell membrane of cell.

Here, all the statements are correct. Hence, your answer will be option [D].

Mitochondria are the tiny-rod shaped organelles which are found in all the cells. Mitochondria provide energy for all the activities of the cell. This energy is produced by the process of respiration in which food is broken down by oxygen. So, mitochondria use glucose and oxygen to produce energy. And in the other hand, nucleus contains thread like structure called chromosomes. Chromosomes contain genes which are the units of inheritance.