Question

The chromosome complement in a moss protonema is:

a. 1n

b. 2n

c. 3n

d. varies with the size of the protonema

Short answer

Option (a) 1n

Step-by-step solution

Step 1. Introduction 

Chromosome compliment: It can be defined as the total number of chromosomes present in a species of any living organism.

Protonema: It is the prime thalloid stage of the gametophyte. It is filamentous and affluent in chlorophyll.

Step 2. Explanation for correct option.

• The protonema is a structure which is extensively found in moss.
• The spores present in moss are of haploid nature i.e., contains only half number of chromosomes.

Hence, 1n is the ploidy of a moss protonema.

Step 3. Explanation for incorrect answer.

• Since, the spore of a moss is haploid in nature and not diploid so 2n is an incorrect ploidy.
• 3n ploidy is invalid as no living organism consist such number of chromosomes.
• The size of any living organism does not affect its chromosome ploidy