Inheritance, Variation and Evolution

• What does asexual reproduction involve? [4] - Only one parent - No fusion of gametes, so no mixing of genetic information - The production of gentically identical offsprings - Mitosis
• How do strawberries reproduce asexually? Sending out long shoots called runners, which touch the ground and grow a new plant
• How do daffodils reproduce asexually? Daffodils produce lots of small bulbs, which can grow into new plants
• How do fungi reproduce asexually? By spores
• How do malaria protists reproduce asexually? When they are in the human host
• What does sexual reproduction involve? It involves the fusion of male and female gametes - Sperm and egg cells in animals - Pollen and egg cells in flowering plants
• What happens when there is a mix of genetic information? It produces variation in the offspring.
• What does the formation of gametes involve? Meiosis
• How does meiosis happen? [6] 1. Cells with two pairs of chromosomes (diploid cell) 2. Each chromosome replicates itself 3. Chromosomes part company and move to opposite poles 4. Cell divides for the first time 5. Copies now separate and the second cell division takes place 6. Four haploid cells (gametes), each with hal the number of chromosomes as the parent cell
• What happen when a cell is divided by meiosis? [3] - Copies of the genetic information are made - The cell divides twice to form four gametes, each with a single set of chromosomes - All gametes are genetically different from each other
• Why is meisos important and what does it mean? [2] - Meiosis is important because it halves the number of chromosomes in gametes. - This means that fertilisation can restore the full number of chromosomes
• What is the genetic material in the nucleus of a cell made of a chemical called? DNA
• What is the DNA contained in? Chromosomes
• What is a gene? A small section of DNA on a chromosome
• What is the genome of an organism? The entire genetic material of that organism
• What important uses does the human genome hold? [3] - Can be used to find out which genes linked to different types of disorder - Helps scientists to understand the cause of inherited disorders and how to treat them - Scientists can investigate how humans may have changed over time
• What are some characteristics controlled by? A single gene
• What may each gene have different forms of? Alleles
• Where does an individual two alleles for each gene come from? [2] - One allele comes from the mother - One allele comes from the father
• What is a genotype? The combination of alleles present in a gene
• What is phenotype? How alleles are expressed
• What two things can alleles either be? [2] - Dominant - Recessive
• What is homozygous? When two alleles present are the same
• What is heterozygous? If the alleles are different
• What is it called when only one gene is involved in controlling most characteristics? Monohybrid inheritance
• What are genetic diagram or punnet squares used for? To predict the outcome of a monohybrid cross
• How are the letters arranged in a genetic diagram or Punnet square? Capital letters for dominant alleles and lower case letters for recessive alleles
• What is polydactyly? Having extra fingers or toes
• How is polydactyly caused? Dominant alleles
• What is Cystic Fibrosis? A disorder of cell membranes
• How is cystic fibrosis caused? Recessive Allele
• What are sex chromosomes? One pair out of the 23 pairs of chromosmes carries genes that determine sex.
• What are the female sex chromosome? XX (identical)
• What are the two male sex chromosome? XY (Y is a shorter chromosome)
• What is the one sex chromosome from the mother? X
• What is the one sex chromosome father? X or Y
• What is variation? Differences in the characteristics of individuals in a population
• Why does variation have differences? [3] - Genes that individuals have inherited - Conditions in which the individuals have developed - Combination of both genetic and enviromental causes
• What happens to alleles during sexual reproduction? Different combinations of alleles are formed, therefore variation.
• What is evolution? [2] - Gradual change in the inherited charcateristics of a population over time. - This may lead to the formation of new species