Inheritance, Variation and Evolution Flashcards
Paper 2 - B6
What is the purpose of meiosis?
Production of gametes (sex cells)
How is mitosis different from meiosis?
Meiosis leads to production of 4 non-identical cells, mitosis leads to production of 2 identical cells
Name the gametes (sex cells) in a) flowering plants b) animals
a) pollen and egg cells b) sperm and egg
Why is sexual reproduction important?
It involves mixing of gametes which leads to variation
What is asexual reproduction?
Reproduction involving only one parent and no fusion of gametes
What type of offspring are produced in asexual reproduction?
Genetically identical organisms (clones)
What does meiosis do to the number of chromosomes in gametes?
It halves the number
Gametes have half the number of chromosomes as body cells. In what process is the full number restored?
Fertilisation
What happens in the nucleus of a cell before meiosis?
Copies of the genetic information (DNA, chromosomes) are made
How many gametes are produced in meiosis?
Four
What type of cell division occurs AFTER fertilisation to lead to an embryo?
Mitosis
What happens to the cells in an embryo to eventually cause organs etc. to develop?
Cells continue to multiply by mitosis and then they DIFFERENTIATE
(Triple only) What is the advantage of sexual reproduction
Produces variation in offspring giving an advantage if the environment changes
(Triple only) Give 4 advantages of asexual reproduction
Only 1 parent needed; more time/energy efficient as don’t need to find a mate; faster than sexual reproduction; many identical offspring produced when conditions are
favourable
(Triple only) Why is genetic variation an advantage?
Natural selection can occur if the environment changes
(Triple only) Name 3 organisms that can reproduce by both sexual and asexual reproduction
Malarial parasites; fungi; plants e.g. daffodils, strawberry plants
(Triple only) Which type of reproduction (asexual or sexual) of malarial parasites occurs in the human host and which occurs in the mosquito?
Asexual in human host, sexual in mosquito
What is the structure of DNA?
Double helix
What is the genome?
The entire genetic material of an organism
What is DNA?
A polymer made up of two strands in a double helix
What structures contain DNA?
Chromosomes
What is a gene?
A small section of DNA on a chromosome
What does a gene code for?
A particular sequence of amino acids to make a specific protein
Give 3 reasons why understanding the human genome is important
Search for genes linked to different diseases; understanding & treatment of inherited disorders; use in tracing human migration patterns from the past