Sexual vs Asexual reproduction
There are two types of reproduction:
-Sexual reproduction
-Asexual reproduction
Sexual Reproduction.
Sexual reproduction is when male and female gametes fuse (join) at fertilisation to form a zygote.
Gametes are sex cells. For example:
Gametes in animals: sperm + egg
Gametes in flowering plants: pollen + egg cell
Gametes are produced by a type of cell division called Meiosis
The gametes (sex cells) produced are genetically different (non-identical), which contribues to variation in the offspring.
Fertilisation mixes genetic information from two parents
Offspring are genetically different (variation)
| Advantages of sexual reproduction | Disadvantages of sexual reproduction |
|---|---|
| Source of genetic variation | Needs two parents |
| If the environment changes, variation in the population means some individuals have traits that give them a survival advantage. These individuals are more likely to survive and reproduce, which is natural selection. | Takes more time, so its slower |
| Natural selection can be speeded up by humans in selective breeding to increase food production. This means humans can use the principles of natural selection to get useful traits faster. | Must find a mate. |
| Uses more energy. |
Asexual reproduction
Asexual reproduction is reproduction that involves only one parent, no fusion of gametes, and produces genetically identical offspring (clones).
Asexual reproduction uses a type of cell division called mitosis which produces genetically identical cells (clones).
| Advantages of asexual reproduction | Disadvantages of asexual reproduction |
|---|---|
| Only one parent needed | No genetic variation |
| Faster reproduction | If the environment changes the organisms may not be able to adapt and they may die out |
| Many genetically identical offspring can be produced when conditions are favourable. This allows an organism to colonise a new habitat. | |
| More time and energy efficient as do not need to find a mate |
Summary table
| Feature | Sexual reproduction | Asexual reproduction |
|---|---|---|
| Parents | Two | One |
| Gametes | Yes | No |
| Fertilisation | Yes | No |
| Cell division | Meiosis | Mitosis |
| Variation | Yes | No |
| Offspring | Genetically different | Genetically identical (clones) |
Practice Questions
1.Strawberry plants can reproduce asexually by producing runners that grow into new plants.
a) How many parents are involved in this type of reproduction?
b)What type of cell division produces the new plants?
c) What word is used to describe offspring that are genetically identical?
Factors affecting the rate of photosynthesis
Measuring & calculating rates of photosynthesis
Inverse square law and photosynthesis
Economics of enhancing the conditions in greenhouses
Investigating the effect of light intensity on the rate of photosynthesis
Data analysis and nervous system
The effect of a factor on human reaction time
Controlling blood glucose concentration
Regulating water and nitrogen levels in the body.
Hormones and human reproduction
Using hormones to treat infertility
Control and coordination in plants using hormones
Investigating the effect of light or gravity on the growth of newly germinated seedlings