Inheritance

• Human cells contain 23 pairs of chromosomes in the nucleus.
• Cells can divide by mitosis, producing two identical cells.
• Gametes, which are the sex cells, contain single chromosomes and are not paired.
• Human sperm and egg cells both contain 23 single chromosomes.
• Gametes are made by a type of cell division called meiosis.
• Unlike mitosis, meiosis produces non-identical cells, meaning every sperm cell and every egg cell are different.
• Meiosis also takes place in flowering plants, where the gametes are pollen and egg cells.
• Both animals and flowering plants carry out sexual reproduction.
• Sexual reproduction involves the fusion of male and female gametes, a process scientists call fertilization.
• In sexual reproduction, there is mixing of genetic information, meaning the offspring will have variation.
• Asexual reproduction involves only one parent, meaning there is no mixing of genetic information and the offspring are all genetically identical, a process scientists call cloning.
• Asexual reproduction does not involve meiosis, only mitosis.
• Aphids reproduce asexually, meaning there is only one parent and the offspring are all genetically identical.
• Plants can reproduce asexually by forming tiny bulbs that drop off and grow into new plants, resulting in genetically identical offspring.
• Meiosis reduces the number of chromosomes and produces gametes.
• Fertilization restores the full number of chromosomes.
• Normal human cells contain 23 pairs of chromosomes.
• Gametes such as sperm and egg cells contain single chromosomes.
• A human gamete contains 23 single chromosomes.
• Meiosis only takes place in reproductive organs in humans, which include the testes in males and the ovaries in females.
• In the first stage of meiosis, all of the chromosomes are copied and the cell divides into two, forming the gametes.
• In the second stage of meiosis, both of these gametes divide one more time, forming four gametes.
• After fertilization, the cell now has the normal number of chromosomes.
• Fertilization is the process where gametes join together.
• Sexual reproduction involves the fusion of gametes, which scientists call fertilization.
• Meiosis produces four gametes from one original cell, and each of these gametes is genetically different from each other.
• Fertilization restores the full number of chromosomes after meiosis reduces the number of chromosomes.
• The full number of chromosomes is restored in fertilization after meiosis reduces the number of chromosomes.
• In fertilization, the new cell divides by mitosis producing a clump of identical cells, which scientists call an embryo.
• As the embryo develops, the cells differentiate forming different cell types, including nerve cells and muscle cells.
• Sexual reproduction is a process where the offspring receive a mixture of genetic information from two parents, producing a variation in the offspring if the environment changes.
• The survival advantage of sexual reproduction is that it gives a species a greater chance of survival if conditions become challenging.
• Humans also take advantage of this variation when they carry out selective breeding.
• Modern strains of wheat have been selectively bred for many years, producing a high yield of good-quality grain.
• Asexual reproduction only requires one parent, making it more efficient in both time and energy than sexual reproduction.
• Asexual reproduction is extremely useful when conditions are favorable, allowing an organism to produce many genetically identical offspring rapidly.
• The risk of asexual reproduction is that all the offspring are genetically identical, meaning they could all die if conditions become unfavorable.
• Some organisms can use sexual reproduction or asexual reproduction depending on the circumstances.
• The malaria parasite has part of its life cycle in a human host and part of its life cycle in a mosquito vector, using sexual reproduction in the human host and asexual reproduction inside the mosquito.
• Many species of fungi reproduce asexually by producing spores.