Biology
Assertion (A): All organisms, whether unicellular or multicellular, start their life from a single celled structure called the zygote.
Reason (R): Zygote is formed by the fusion of two unicellular structures (gametes) during the process of fertilization among higher plants and animals.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Answer
Both A and R are true and R is the correct explanation of A.
Reason — A is true as in sexual reproduction, both unicellular and multicellular organisms begin development from a single cell called the zygote.
R is true as a zygote is formed when two gametes (sperm and egg), which are unicellular structures, fuse during fertilization in higher plants and animals.
The formation of a single-celled zygote through fertilization explains why organisms start life from a single cell.
Therefore, Both A and R are true and R is the correct explanation of A is the correct option.
Related Questions
Assertion (A): Meristematic tissues consist of undifferentiated, actively dividing cells.
Reason (R): Meristems are undifferentiated as they divide and redivide and produce a large number of cells. They are not specialized for any particular function.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Assertion (A): Permanent tissues form the bulk of the plant body and they do not divide.
Reason (R): Permanent tissues mature into fixed, specialised cells that carry out specific functions, so they no longer retain the ability to divide.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Assertion (A): Blood and lymph, both contain the same fluid (plasma) but they differ from each other in their cellular contents.
Reason (R): Blood contains red blood cells and platelets whereas lymph contains only white blood cells.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Assertion (A): Epithelial tissues form a protective covering of cells, found only on the outer surface of the body.
Reason (R): Epithelial tissues are also found around internal organs, line inner body surfaces and perform various functions like absorption, secretion, etc.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.