Inheritance

• What is sexual reproduction?


  A type of reproduction involving the production of gametes by meiosis.
• How is a zygote formed in sexual reproduction?


  A gamete from each parent fuses to form a zygote.
• What is unique about the resulting zygote in sexual reproduction?


  It has mixed genetic information from each gamete, making it unique.
• What are gametes?


  Sex cells such as sperm and egg cells in animals, and pollen and egg cells in flowering plants.
• What is the chromosome number of gametes?


  Gametes are haploid, meaning they have half the number of chromosomes.
• What is meiosis?


  A form of cell division involved in the formation of non-identical haploid gametes in reproductive organs.
• What happens to the chromosome number during meiosis?


  The chromosome number is halved.
• How many divisions are involved in meiosis?


  Meiosis involves two divisions.
• What must occur prior to meiosis?


  Interphase, where copies of genetic information are made.
• What happens during the first stage of meiosis?


  Chromosome pairs line up along the cell equator and are separated to opposite poles.
• What is the significance of the random separation of chromosomes during meiosis?


  It creates variation in the resulting gametes.
• What happens during the second stage of meiosis?


  Chromosomes line up along the cell equator, and the chromatids are separated to opposite poles.
• What is produced at the end of meiosis?


  Four unique haploid gametes.
• Why is meiosis important for sexual reproduction?


  It increases genetic variation and ensures the zygote is diploid.
• What occurs during fertilisation?

  Gametes join together to restore the normal number of chromosomes.
• What happens after fertilisation?


  The new cell divides by mitosis, increasing the number of cells.
• What happens as the embryo develops after fertilisation?


  Cells differentiate.
• What is the advantage of sexual reproduction?

  It creates genetic variation in offspring, increasing survival chances.
• How can natural selection be influenced by sexual reproduction?


  Natural selection can be speeded up by humans in selective breeding.
• What is a disadvantage of sexual reproduction?


  Two parents are required, making reproduction difficult in some situations.
• What is another disadvantage of sexual reproduction?


  It requires more time and energy, resulting in fewer offspring.
• What is asexual reproduction?


  A type of reproduction that involves mitosis only.
• What is produced in asexual reproduction?


  Genetically identical offspring known as daughter cells.
• What is an advantage of asexual reproduction?


  Only one parent is required.
• How does asexual reproduction enable rapid colonisation?


  Lots of offspring can be produced in a short period of time.
• Why does asexual reproduction require less energy and time?


  It does not need a mate.
• What is the disadvantage of asexual reproduction?


  No genetic variation, reducing adaptability to environmental changes.
• In which organism does sexual reproduction occur in mosquitoes?


  In malarial parasites.
• Where does asexual reproduction occur in malarial parasites?


  In the human host.
• How do fungi reproduce asexually?


  By spores.
• Why do fungi reproduce sexually?


  To give variation.
• How do plants reproduce sexually?


  To produce seeds.
• What is a method of asexual reproduction in plants?


  By runners or bulb division.
• What is DNA?


  A double-stranded polymer of nucleotides forming a double helix.
• Where is DNA found in a cell?


  In the nucleus.
• Define genome.


  The entire genetic material of an organism.
• Why is understanding the human genome important?


  It aids in the development of medicine and understanding diseases.
• What is a chromosome?


  A long, coiled molecule of DNA that carries genetic information.
• How many chromosomes do human body cells have?


  46 chromosomes (23 pairs).
• How many chromosomes do human gametes have?


  23 chromosomes.