Class 8 Science Chapter 8 MCQ

The organisms which are made of single cell are called unicellular organisms. The single cell behaves as a complete organism performing basic functions such as respiration, reproduction, nutrition, movement etc.

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

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).

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.

Various components of cells are called cell organelles. Tissue is a group of similar cells which work together to perform a particular function. 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.

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.

Xylem cells are the tube-like plant cell having thick and strong walls which carry water from roots of the plant to its leaves.

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.

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.

An amoeba cell and white blood cell present in human blood can change their shape

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

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

Cell membrane is the common part of every cell. It encloses the protoplasm, protects the cell, gives the cell its shape and control the entry and exit of substances.

Chromosomes are the thread-like structures present in the nucleus. They contain genes that functions to transfer the characteristics from the parents to the offsprings.

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.

Virus is not considered a cell. It is an exception to the cell theory and cannot survive on its own.

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].

Prokaryotes do not have a well-defined nucleus. The irregularly-shaped region that contains their genetic material is called nucleoid. The other statements in correct form are: Tissue is a group of similar cells. And organ consists of different tissues. Large vacuoles are found in plant cells.

The cells having well defined nucleus containing nuclear material, enclosed by a nuclear membrane are called eukaryotic cells. Example cheek cells. Blue green algae are prokaryotic cells that do not have a nuclear membrane.