CB2 set pieces

• Reaction time required practical

  Hold a ruler (just) above the (open) hand of the other student.• Drop the ruler and other student catches it. • Record where the ruler is caught
• Hormones of the menstrual cycle

  Follicle stimulating hormone (FSH) causes maturation of an egg in the ovary. (produced by pituitary)• Luteinising hormone (LH) stimulates the release of the egg. (produced by pituitary)• Oestrogen and progesterone are involved in maintaining the uterus lining. (both produced by ovary / follicle)
• In Vitro Fertilisation (IVF)

  IVF involves giving a mother FSH and LH to stimulate the maturation of several eggs.• The eggs are collected from the mother and fertilised by sperm from the father in the laboratory. • The fertilised eggs develop into embryos.• At the stage when they are tiny balls of cells, one or two embryos are inserted into the mother's uterus (womb).
• Meiosis (making gametes/sex cells)

  When a cell divides to form gametes: 

  • 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
• Importance of understanding the human genome

  Search for genes linked to different types of disease• understanding and treatment of inherited disorders • use in tracing human migration patterns from the past.
• Natural selection

  Variation in the population caused by mutation,• Best adapted to the environment survive and • reproduce,• Genes passed on.
• Become a new species

  If populations are isolated and become so different that they can no longer breed to produce fertile offspring.
• Selective breeding

  Selective breeding involves choosing parents with the desired characteristic from a mixed population. • They are bred together. • From the offspring those with the desired characteristic are bred together.• This continues over many generations• until all the offspring show the desired characteristic
• Examples of uses of selective breeding

  Disease resistance in food crops. • Animals which produce more meat or milk. • Domestic dogs with a gentle nature. • Large or unusual flowers.
• Genetic engineering

  Selective breeding can lead to ‘inbreeding’ where some breeds are particularly prone to disease or inherited defects.

  Genetic engineering:

  • enzymes are used to isolate the required gene; this gene is inserted into a vector, usually a bacterial plasmid or a virus• the vector is used to insert the gene into the required cells• genes are transferred to the cells of animals, plants or microorganisms at an early stage in their development so that they develop with desired characteristics.
• Examples of uses of genetic engineering

  GM crops include ones that are resistant to insect attack or to herbicides. GM crops generally show increased yields.

   

  Modern medical research is exploring the possibility of genetic modification to overcome some inherited disorders.

   

  Concerns about GM crops include the effect on populations of wild flowers and insects. Some people feel the effects of eating GM crops on human health have not been fully explored
• Reducing the rate of development of antibiotic resistance

  • doctors should not prescribe antibiotics inappropriately, such as treating non-serious or viral infections• patients should complete their course of antibiotics so all bacteria are killed and none survive to mutate and form resistant strains • the agricultural use of antibiotics should be restricted.
• carbon cycle

  Photosynthesis by plants and algae (CO2 à Glucose)

  Respiration by plants, algae, microbes and animals (Glucose à CO2)

  Feeding by consumers

  Decay by microbes and other decomposers.
• Greenhouse effect

  short wavelength radiation which enters the atmosphere • is absorbed by materials and re-emitted• as a longer wavelength radiation (IR)

  (which is absorbed / trapped by)

  • greenhouse gases / carbon dioxide / methane which stops radiation escaping (from the atmosphere)
• Sampling an area using a quadrat

  Calculate the area of the habitat.

  Random placement of quadrat a suitable number of times (more than 10)

  Calculate mean number of organisms per quadrat. 

  Calculate mean number per m2 (x4 if a 0.5m x 0.5m quadrat)

  Multiply number per m2 by total area of habitat.
• Sampling along a transect

  Improve estimate by taking a greater number of quadrats and improving the randomness of placement.

  Sampling along a transect

  Mark out transect using a tape measure.

  Place quadrat at regular intervals next to the transect.

  Count number of individuals of each species present in quadrat.