What Is Reproduction?
Reproduction
The process by which living organisms produce new individuals to ensure the continuation of their species.
- Reproduction is the process by which living organisms produce new individuals.
- It ensures the continuation of a species from one generation to the next.
- For reproduction to work, organisms must pass on their genetic information (DNA) to offspring.
- All forms of reproduction rely on copying and transmitting DNA to create a new individual.
What Are the Types of Reproduction?
Organisms reproduce in two main ways, depending on how genetic information is passed on.
Asexual reproduction
- One parent produces offspring.No gametes (sperm or egg cells) are involved.
- Offspring are genetically identical to the parent because only mitosis is used.
- It is fast and efficient, allowing populations to increase quickly.
- The downside is no genetic variation.
- Bacteria dividing by binary fission
- Strawberry plants producing runners
- Potato tubers forming new plants
Asexual reproduction does not involve meiosis or fertilization.
Sexual reproduction
- Two parents produce gametes (sperm and eggs).
- Gametes are made by meiosis, so each contains half the usual chromosome number.
- Fertilization combines the gametes to form a zygote with a full set of chromosomes.
- Offspring are genetically unique, creating variation in a population.
- Humans
- Flowering plants
- Most animals
More on variation in the next article.
What Changes Happen at Puberty in Males and Females?
Puberty
The period when physical and reproductive maturity develops.
- Puberty begins when the hypothalamus signals the pituitary gland.
- The pituitary releases hormones that trigger reproductive development in the ovaries or testes.
Changes That Occur in Males at Puberty
- Testosterone triggers physical and reproductive changes:
- Sperm production begins
- Voice deepens
- Shoulders broaden
- Muscle mass increases
- Facial, body, and pubic hair grows
- Growth spurts occur
After puberty, males produce millions of sperm continuously.
Changes That Occur in Females at Puberty
- Oestrogen triggers reproductive development and the start of menstrual cycles.
- Ovulation begins
- Menstrual cycle starts
- Breasts develop
- Hips widen
- Pubic and underarm hair grows
- Growth spurts occur
Typically, one egg matures and is released roughly every 28 days.
How Do Gametes Differ Between Males and Females?
Gamete
A reproductive cell (sperm or egg) that contains half the usual number of chromosomes.
| Feature | Sperm (Male Gamete) | Egg (Female Gamete) |
|---|---|---|
| Size | Small | Female |
| Mobility | Mobile; uses a tail to swim | Non-mobile |
| Number produced | Millions produced continuously | One released roughly every 28 days |
| Energy content | Very little stored energy | Nutrient-rich to support early development |
| Function | Deliver genetic material to the egg | Provide genetic material and nutrients |
The egg contains stored nutrients to support early development before the placenta forms.
Sperm and eggs both carry DNA, but eggs are much larger because they support early growth.
How Does Fertilization Lead to a New Individual?
- Fertilization occurs when a sperm fuses with an egg to form a zygote.
- Steps in fertilization:
- Sperm travel through the female reproductive system to reach the egg.
- One sperm fuses with the egg’s membrane.
- The genetic material from each gamete combines.
- Because each gamete contains half the chromosome number, the zygote regains the full number.
- The zygote divides repeatedly by mitosis, forming an embryo.
- Mitosis ensures each new cell in the embryo receives identical DNA.
Fertilization is like combining two halves of a code to produce the full instruction set for a new organism.
- What are the differences between sexual and asexual reproduction?
- How does meiosis contribute to variation?
- What hormonal changes occur at puberty in males and females?
- Why do gametes differ structurally?
