Comparing Sexual & Asexual Reproduction
- Sexual reproduction involves two parents and is the fusion of the nuclei of two gameteto form a zygoteand the production of offspring that are genetically different from each other
- A gamete is a sex cell (in animals: sperm and ovum; in plants: pollen nucleus and ovum)
- Gametes differ from normal cells as they contain half the number of chromosomes found in other body cells - we say they have a haploid nucleus
- This is because they only contain one copy of each chromosome, rather than the two copies found in other body cells
- In human beings, a normal body cell contains 46 chromosomes but each gamete contains 23 chromosomes
- When the male and female gametes fuse, they become a zygote (fertilised egg cell)
- This contains the full 46 chromosomes, half of which came from the father and half from the mother - we say the zygote has a diploid nucleus
- A gamete is a sex cell (in animals: sperm and ovum; in plants: pollen nucleus and ovum)
- There are number advantages and disadvantages to an organism carrying out sexual reproduction
Advantages & disadvantages of sexual reproduction table
- Asexual reproduction
- Asexual reproduction does not involve gametes or fertilisation
- Only one parent is required so there is no fusion of gametes and no mixing of genetic information
- As a result, the offspring are genetically identical to the parent and to each other (they are clones)
- Many plants reproduce via asexual reproduction
- Bacteria produce exact genetic copies of themselves in a type of asexual reproduction called binary fission
- Asexual reproduction does not involve gametes or fertilisation
- There are a number of advantages and disadvantages to an organism carrying out asexual reproduction
Advantages & disadvantages of asexual reproduction table
- The key differences between sexual and asexual reproduction include:
- The number of parent organisms
- How offspring are produced (the type of cell division required)
- The level of genetic similarity between offspring
- The possible sources of genetic variation in offspring
- The number of offspring produced
- The time taken to produce offspring
Comparing sexual & asexual reproduction table
