B6

• State the difference between sexual and asexual reproduction.


  Sexual reproduction involves 2 parents and the offspring are genetically different. Asexual reproduction involves one parent and the offspring are genetically identical.
• Name the male and female gametes of animals.

  Egg and sperm.
• Define the term alleles.

  Different versions of the same gene.
• Define the term genotype.

  The combination of alleles you have.
• Define the term phenotype.

  . The characteristics you have as a result of your genotype.
• Define the term homozygous.

  2 alleles for a gene that are the same.
• Define the term heterozygous.

  2 alleles for a gene that are different.
• What is the term given for the joining of gametes?

  Fertilisation.
• What 2 factors can affect variation in organisms?

  Environmental and genetic.
• What part of the cell does cystic fibrosis affect?

  Cell membrane.
• Is Polydactyly dominant or recessive?


  Dominant.
• What are the chances of a child being born with XX chromosomes?

  50%
• State the number of daughter cells produced during mitosis.

  2
• How many chromosomes are found in human gametes?

  23
• What sex is a child born with XY chromosomes?


  Male.
• State the type of cell division that makes gametes.

  Meiosis.
• Place these in order of size from smallest to biggest: nucleus, gene, chromosome, DNA.


  Gene, chromosome, DNA, nucleus.
• What is meant by the term mutation?

  A random change in genes.
• What is speciation?


  The formation of a new species from an existing species.
• State 3 causes of extinction.

  New predators, disease, environment change, competition.
• Name the groups that organisms are classified in the Linnaean system.

  Kingdom, phylum, class, order, family, genus, species.
• Who developed the idea of natural selection?

  Charles Darwin.
• What must occur for natural selection to happen?

  Variation and selective pressure.
• Define the term genetic engineering.

  Modifying the genome of an organism to produce a desired effect.
• What hormone have bacteria been engineered to produce?


  Insulin.
• What is meant by selective breeding?

  Selecting organisms with desired characteristics to breed to produce ideal offspring.
• What is a fossil?

  The preserved remains of long dead organisms.
• Define DNA.


  A polymer made up of two strands forming a double helix.
• Define Gene.


  A small section of DNA that codes for a protein.
• Define chromosome.


  A collection of genes.
• Define nucleus.


  A cell organelle that contains chromosomes.
• Define recessive.


  An allele that is only expressed if there are 2 copies of it.
• Define dominant.


  An allele that is always expressed if present.
• What four bases make up DNA?

  A, T, C, G​
• What complementary pairs occur in the structure of DNA?

  A + T, C + G​
• How might a mutation affect the structure of a protein?


  Either no effect, or change the shape of the protein​
• Why might mutations be negative?

  A differently shaped protein/ enzyme, may not do its original job.​
• What are the four methods of cloning?

  Adult cell cloning, embryo transplants, tissue culture, cuttings.
• What scientist developed ideas about inheritance?

  Gregor Mendel​
• Who developed the idea of speciation?

  Russel Wallace​