Difference Between Haploid and Diploid Cells, Practice Problems and FAQs

Chromosomes are those thread-like structures seen inside the cell nucleus that carry all our genetic information. They are responsible for generating the similarities between you and your parents. Have you ever thought about the science behind the similarities you have with both of your parents? The similarities can be morphological or behavioural. The reason behind this occurs during the meiosis division in the formation of the egg from your mother and sperm from your father. The sperm and egg are called the gametes and they carry only half the number of chromosomes (n). So that when they fuse and form the zygote (2n), it will have the correct number of chromosomes that an individual needs.

Fig: Fertilisation between male and female gametes

But in a human individual, the number of chromosomes varies in different cells. Right? How is that possible? It is because of the two different types of division called the meiosis (reduction division) and the mitosis (equational division). The gametes are formed after meiosis and most of the other cells in the humans are formed through mitosis. We can call the gamete cells as haploid cells (n) and other cells like the skin cells as diploid cells (2n). So what all can be the differences between haploids and diploids? We are going to discuss more about the differences between them in this article.

Table of contents

• Haploid
• Diploid
• Difference between haploid and diploid cells
• Practice Problems
• FAQs

Haploid

Those cells which contain only one set of chromosomes are called haploid cells. The most common types of haploid cells are gametes or sex cells. Those somatic cells having half the number of chromosome sets can be also called haploid cells. Haploid cells are genetically diverse and they are produced through meiosis or reduction division. Cells with a single set of chromosomes are also called monoploids and this condition is called monoploidy or haploidy.

Fig: Haploid cell

Gametes helps to maintain the constant number of chromosomes in the sexually reproducing organisms. In humans the total number of chromosomes in sex cells are 23.

Examples of haploids

The major examples of haploids are as follows:

• Gametes (sperm and ova)

Fig: Gametes

• Males of bees, wasps and ants (develop from unfertilised haploid eggs) belong to the order Hymenoptera.

Fig: Haploid organisms

Diploid

Those cells which contain two homologous copies of each chromosome (two sets of chromosomes) are called diploid cells. One set of chromosomes will be from the mother (maternal) and another set of chromosomes will be from the father (paternal). The fusion of two haploid cells results in the formation of a diploid cell. They then multiply by mitosis.

Fig: Diploid cell

All the somatic cells of humans are diploid. In humans all the cells except the proliferating cells of the reproductive system are coming under the somatic cells.

The chances for causing spontaneous mutation is higher in diploid cells than in haploid cells. 220 types of somatic cells are seen in humans. The total number of chromosomes in the somatic cells of humans are 46.

Fig: Human chromosomes

Examples of diploids

The major examples of diploids are as follows:

• Somatic cells of humans like blood cells, skin cells and muscle cells.

Fig: Human somatic cells

• Most mammal cells.
• Cells of fishes.
• Sporophytic plant cells like stem, leaf etc., as plants show both haploid (gametophyte) and diploid stages in their life cycle.

Fig: Diploid organisms

Difference between haploid and diploid cells

The major difference between haploid and diploid cells are as follows:

Practice Problems

1. Which of the following statements is incorrect about haploid cells?

1. Cells have only one set of chromosomes
2. The most common types of haploid cells are somatic cells
3. They are produced through meiosis or reduction division
4. Cells with a single set of chromosomes are called monoploids

Solution: Those cells which contain only one set of chromosomes are called haploid cells. The most common types of haploid cells are gametes or sex cells. Those somatic cells having half the number of chromosomes in the somatic cells can be also called haploid cells. Haploid cells are genetically diverse and they are produced through meiosis or reduction division. Cells with a single set of chromosomes are also called monoploids and this condition is called monoploidy or haploidy. Hence the correct option is b.

Fig: Haploid cell

2. Which of the following organisms are haploids?

1. Male bees
2. Male wasps
3. Male ants
4. All the above

Solution: Those cells which contain only one set of chromosomes are called haploid cells. The most common types of haploid cells are gametes or sex cells. There are some organisms that develop from unfertilised haploid eggs. Such organisms will be haploid organisms. Some of the examples are male bees, wasps and ants belonging to the order Hymenoptera. Hence the correct option is d.

Fig: Haploid organisms

3. Choose the options suitable for a diploid cell.

i) One set of chromosomes will be from the mother and another set of chromosomes will be from the father.
ii) They are produced through meiosis.
iii) All the somatic cells of humans are diploid.
iv) They develop from fertilised eggs.
v) The cells are not genetically similar to the parent cells, because of crossing over.

1. i, ii, iii, iv, and v
2. i, iii, and iv
3. i, ii, and v
4. iii, iv, and v

Solution: The cells which contain two homologous copies of each chromosome (two sets of chromosomes) are called diploid cells. One chromosome set will be from the mother (maternal) and another set of chromosomes will be from the father (paternal). The fusion of two haploid (n) cells results in the formation of a diploid cell (2n). They then multiply through mitosis. All the somatic cells of humans are diploid. In humans all the cells except the proliferating cells of the reproductive system are coming under the somatic cells. They develop from fertilised eggs. The cells are genetically similar to the parent cells. Hence the correct option is b.

Fig: Diploid cell

4. Find the option having all diploid cells from the following.

1. Skin cells, muscle cells and blood cells
2. Skin cells, muscle cells and sperm cells
3. Egg cells, muscle cells and blood cells
4. All the above

Solution: The cells which contain two homologous copies of each chromosome (two sets of chromosomes) are called diploid cells. One chromosome set will be from the mother (maternal) and another set of chromosomes will be from the father (paternal). The fusion of two haploid (n) cells results in the formation of a diploid cell (2n). They then multiply through mitosis. All the somatic cells of humans are diploid. In humans all the cells except the proliferating cells of the reproductive system are coming under the somatic cells. Examples of somatic cells of humans are blood cells, skin cells, muscle cells etc. Hence the correct option is a.

Fig: Human somatic cells

FAQs

1. What is the alternation of generations?
Answer: The alternation between the haploid and diploid stages of life is called alternation of generations. It is seen in all plants, many fungi and algae. Sometimes one stage dominates over the other stage. For example, the life cycle of bryophytes like mosses.

Fig: Life cycle of a bryophyte

2. What is polyploidy?
Answer: The state where all cells have multiple sets of chromosomes compared with the basic set is called polyploidy. The different types of polyploidies are as follows:

• Triploid (3 sets)
• Tetraploid (4 sets)
• Pentaploid (5 sets)
• Hexaploid (6 sets)
• Heptaploid (7 sets) etc.

Examples include Triticale, an allotetraploid formed from crossing wheat (Triticum) and rye (Secale).

Fig: Triticale

3. Which organism has the highest number of chromosomes?

Answer: The highest number of chromosomes is recorded in a fern called adder's tongue fern or Ophioglossum reticulatum. It has 1440 chromosomes or 720 pairs of chromosomes.

Fig: Ophioglossum reticulatum

4. What is mixoploidy?
Answer: The case where two cell lines (one diploid and one polyploid) coexist in the same organism is called mixoploidy.