46 chromone in a zygote

Question: 15 of 47

CORRECT

• Time Remaining: 07:59:19

Which of the following options represents the chromosomal composition of a normal human zygote?

23 chromosomes

The unfertilized egg and the sperm each contain 23 chromosomes. This is the haploid chromosome number for a human.

46 chromosomes

MY ANSWER

The fusion of a sperm with 23 chromosomes and an egg with 23 chromosomes would result in a zygote with 46 chromosomes.

69 chromosomes

69 chromosomes represent the fusion of a diploid human cell with a haploid human cell. This is not the diploid chromosome number for a normal human zygote.

92 chromosomes

92 chromosomes represent the fusion of two diploid human cells. This is not the chromosome number for a normal human zygote 

What is a Zygote?

• A zygote is the very first cell formed when a sperm cell (from the father) fertilizes an egg cell (from the mother).

• It contains a complete set of chromosomes — half from the father and half from the mother.

• This zygote is the starting point of a new organism. It keeps dividing and developing into an embryo.

👉 Example: In humans, the zygote has 46 chromosomes (23 from sperm + 23 from egg).

---

What is Hemi-zygote?

• “Hemi” means “half.”

• A hemizygote is when an individual has only one copy of a gene instead of the usual two.

• This most often happens with sex chromosomes (X and Y):

  • Males (XY) are hemizygous for genes on the X chromosome, because they only have one X (unlike females who have two Xs).

• Example: If a gene is located on the X chromosome, a male has only one version of it (from the mother). That makes him hemizygous for that gene.

---

✅ In short:

• Zygote = first fertilized cell (egg + sperm).

• Hemizygote = having only one copy of a gene (instead of two), usually seen in X-linked genes in males.