Problem 6 - Biology of Humans: Concepts, Applications, and Issues

Question

A zygote a. is the cell formed when the sperm fertilizes the egg. b. will develop into a gamete. c. contains one complete set of chromosomes. d. usually forms in the endometrium.

Step-by-Step Solution

Answer

Option (a) is correct.

Step 1: Understand the definition of a Zygote

A zygote is the cell formed when a sperm cell fertilizes an egg cell. This fertilization marks the beginning of a new organism.

Step 2: Analyze each option

Option (a): This matches the definition of a zygote. Option (b): A zygote develops into an embryo, not a gamete. Option (c): A zygote contains two complete sets of chromosomes (one from each parent), so this is not accurate. Option (d): A zygote typically forms in the fallopian tube, not the endometrium.

Step 3: Identify the correct option

Based on the analysis, option (a) is the correct answer because it accurately describes a zygote.

Key Concepts

Fertilization Process

Fertilization is a crucial biological process. It occurs when a sperm cell from a male merges with an egg cell from a female. This union happens in the fallopian tube. Once the sperm penetrates the egg, their nuclei combine. This results in the formation of a new cell called the zygote.

Fertilization not only marks the beginning of a new organism but also activates genetic material. This activation is essential for the next stages of development.

It's essential to understand that fertilization is just the first step in a series of complex events. These events lead to the creation of a new individual.

Chromosome Sets

Chromosomes are structures within cells that contain DNA. Each parent contributes one set of chromosomes during fertilization.

In humans, this means:

• A sperm cell (from the father) brings 23 chromosomes.
• An egg cell (from the mother) brings 23 chromosomes.

When they merge to form a zygote, the zygote ends up with 46 chromosomes. This is called a diploid state.

It's important to note that the combination of chromosomes determines the genetic makeup. This mixture is critical for genetic diversity among humans. Every individual has a unique combination of these chromosome sets.

Embryo Development

After fertilization, the zygote begins to divide. This process is known as cell division or mitosis.

During this stage:

• The zygote divides into two cells, then four, then eight, and so on.
• These divisions lead to a structure called a blastocyst.
• The blastocyst implants itself into the endometrium (the lining of the uterus).

This is where it starts its journey towards becoming an embryo.

As the cells continue to divide, they start to specialize. This specialization is necessary for forming different tissues and organs. By the time the cells have developed into an embryo, they're on their way to forming a fully functional human being.