The Fundamental Unit of Life Test - 17

The word karyon means the part of a cell containing DNA and RNA. It is responsible for growth and reproduction. Unlike prokaryotes, eukaryotes have a true nucleus. Hence, living organisms are grouped into eukaryotes and prokaryotes on the basis of nucleus.

The correct answer is B.

Why alternatives A, C and D are wrong:

Only living organisms are grouped on the basis of nucleus. Hence, alternatives A, C, and D are incorrect.

Unicellular organisms are made up of a single cell. Corals are not unicellular organisms. They are the simplest form of multi-cellular organisms.

The correct answer is B.

Why alternative A is wrong:

Bacteria are the simplest form of unicellular organisms.

Why alternative C is wrong:

Yeasts are unicellular organisms. They are made up of a single cell.

Why alternative D is wrong:

Archaea are single-celled or unicellular organisms.

Prokaryotic cells do not have a membrane bound nucleus or a ‘true nucleus’. Hence, structurally, they are simpler than eukaryotic cells. Cell division in prokaryotic cells takes place through the process of binary fission.

The correct answer is D.

Why alternatives A, B and C are wrong:

Prokaryotes are the simplest form of unicellular organisms. They do not have a membrane bound nucleus. Prokaryotes divide through the process of binary fission. Hence, alternatives A, B, and C are incorrect.

Plasma membrane or cell membrane is a thin sheet composed of proteins and phospholipids. It regulates the substances moving in and out of cells.

The correct answer is C.

Why alternative A is wrong:

Cell wall protects and gives structural support to cells.

Why alternative B is wrong:

Nucleus contains the genetic material i.e., DNA.

Why alternative D is wrong:

Cell wall maintains the shape of cells.

Plasma membrane or plasmalemma forms the outermost layer in animal cells.

The correct answer is B.

Why alternative A is wrong:

Mitochondria are cell organelles in which ATP is formed. They are not the outermost layers of animal cells.

Why alternative C is wrong:

Cell wall is absent in animal cells.

Why alternative D is wrong:

Nuclear membrane is a double membrane system outside the nucleus. It is not the outermost layer of animal cells.

The nucleus of a cell contains the genetic material i.e., DNA. The molecules of DNA are located in chromosomes.

The correct answer is D.

Why alternatives A, B and C are wrong:

The molecules of DNA are located in chromosomes. Hence, alternatives A, B, and C are incorrect.

In multi-cellular organisms, cells are usually dependent upon each other i.e., each cell functions in co-ordination with other cells.

The correct answer is B.

Why alternative A is wrong:

In multi-cellular organisms, cells are dependent upon each other. Hence, this alternative is incorrect.

Why alternative C is wrong:

In multi-cellular organisms, cells are capable of transporting substances. Hence, this alternative is incorrect.

Why alternative D is wrong:

In multi-cellular organisms, cells are capable of multiplication. Hence, this is alternative is incorrect.

DNA molecules combine with large varieties of proteins, such as histones, to form chromosomes. Genes are present within these chromosomes.

The correct answer is B.

Why alternatives A, C and D are wrong:

DNA molecules combine with large varieties of proteins, such as histones, to form chromosomes. Hence, alternatives A, C, and D are incorrect.