Question

The cells of endosperm have 24 chromosomes. What will be the number of chromosomes in the gametes?

• A. 8
• B. 16
• C. 23
• D. 32

Hint:

Always remember the golden ploidy ratio in Angiosperms: - Gamete = $n$ - Somatic Cell Root Leaf = $2n$ - Endosperm = $3n$ Simply divide the endosperm chromosome count by 3 to find the gametic count!

Answer 1

The Correct Option is A

Concept: Angiosperms exhibit a unique reproductive process called double fertilization. One male gamete fuses with the egg cell to form a diploid ($2n$) zygote. The second male gamete fuses with the diploid secondary nucleus (or two haploid polar nuclei) in the central cell to produce a triploid ($3n$) Primary Endosperm Nucleus (PEN), which subsequently develops into the nutrient-rich endosperm tissue.
• Ploidy of Endosperm = Triploid ($3n$)
• Ploidy of Gametes (both male and female) = Haploid ($n$)
• Ploidy of somatic cells Zygote = Diploid ($2n$)

Step 1: Set up the algebraic ploidy relationship.
We are given that the cells making up the endosperm possess 24 chromosomes. Since endosperm tissue in flowering plants is triploid, we can write down the mathematical equality: \[ 3n = 24 \]

Step 2: Solve for the haploid set variable ($n$).
To isolate the variable $n$, which represents the fundamental basic chromosome number of a single genome set, we divide both sides of the equation by 3: \[ n = \frac{24}{3} \Rightarrow n = 8 \]

Step 3: Relate the haploid set to gametic chromosome counts.
Gametes (sperm cells and egg cells) are formed via meiosis and are invariably haploid ($n$). Therefore, the number of chromosomes found within a gamete of this particular plant species must equal $n$. \[ \text{Number of chromosomes in the gamete} = n = 8 \] This aligns perfectly with Option (A).