Asexual Reproduction

• Reproduction is a fundamental characteristic of living things.
• Organisms reproduce through either asexual or sexual reproduction.

Asexual Reproduction

• In asexual reproduction, a new organism obtains chromosomes from one parent.
• Only one parent is involved in asexual reproduction.
• Cell division in asexual reproduction is called mitosis.
• This cell division produces new cells that contain identical genes to the parent cell.
• Offspring are genetically identical to each other and their single parent.
• Asexual reproduction does not involve fertilization or gametes (sex cells).
• Asexual reproduction is the process resulting in the production of genetically identical offspring from one parent.

Advantages of Asexual Reproduction

• Population can increase rapidly.
• Asexual reproduction can exploit a suitable habitat quickly.
• No mate is needed.
• No gametes are needed.
• All the good characteristics of the parent are passed on to the offspring.
• Offspring will grow in the same favorable environment as the parent.
• Asexually reproducing plants usually store large amounts of food for rapid growth when conditions are suitable.

Disadvantages of Asexual Reproduction

• Asexual reproduction does not lead to variation in a population.
• The species may only be suited to one habitat.
• Disease may affect all individuals in a population.
• There is little variation created, so adaptation to a changing environment is unlikely.
• If the parent has no resistance to a particular disease, the offspring will have no resistance.
• Lack of dispersal can lead to competition for nutrients, water, and light.

Sexual Reproduction

• In this type of reproduction, the parent organism produces sex cells called gametes.
• Eggs and sperm are examples of gametes.
• Two gametes join, and their nuclei fuse together which is called fertilization.
• The new cell formed by fertilization is called a zygote.
• Zygote divides and grows into a new organism.
• Contains chromosomes from both parents.
• Offspring are genetically different from each other and from their parents.
• Gametes are different from ordinary cells because they contain only half as many chromosomes.
• When two of them fuse together, the zygote has the correct number of chromosomes.
• Human body cells have 46 chromosomes.
• Human egg and sperm cells have only 23 chromosomes each.
• The zygote formed when egg and sperm fuse together has 46 chromosomes.
• A cell with the full number of chromosomes, with two complete sets, is called a diploid cell.
• An egg or sperm has 23 chromosomes and is a single set, called a haploid cell.
• Gametes are always haploid.
• When two gametes fuse together, they form a diploid zygote.
• Cells of a eucalyptus tree have 22 chromosomes.
• Their gametes have 11 chromosomes each.
• The zygote inside its seed has 22 chromosomes.

Advantages of Sexual Reproduction

• Introduces variation into a population.
• The species can adapt to new environments.
• A disease is less likely to affect all individuals in a population.
• There is variation in the offspring, so adaptation to a changing or new environment is likely.
• New varieties with disease resistance can be created.
• Seeds allow dispersal from the parent plant, reducing competition.

Disadvantages of Sexual Reproduction

• Time and energy are needed to find a mate.
• It is not possible for an isolated individual to reproduce sexually.
• Two parents are usually needed.
• Growth of a new plant to maturity from a seed is slower.