exam q

• Name the type of cell division that produces egg cells and sperm cells.


  meiosis
• Sexual reproduction produces offspring that are genetically different from each other. Give two reasons why sexual reproduction causes variation in the offspring?


  eggs and sperm are not genetically identical

  there is a mixing of genetic information
• A person with the genotype DD is homozygous. What word describes the genotype Dd?


  heterozygous
• Embryos can be screened for the alleles that cause inherited disorders. Give two advantages of embryo screening


  can find out if the embryo has an inherited disorder

  can decide whether to continue with the pregnanc
• Why is the percentage of species that are extinct only an estimate


  humans have not found evidence of every species
• What evidence is used to study species that have become extinct?

  fossils
• Explain how the evolution of antibiotic resistant bacteria can be slowed down


  Doctors should not prescribe antibiotics inappropriately so fewer amount of bacteria are exposed to antibiotics and stop using antibiotics to treat mild bacterial infection because the immune system can respond to it. Also, do not use antibiotics to treat any viral infections because antibiotics do not kill viruses and patients should complete their course of antibiotics so its more likely that all the bacteria is killed. Additionally, hand washing after going to toilet will reduce the spread of disease.
• Describe a method to investigate how the distance from the river affects the number of different plant species in the field


  Start by measuring a line at right angles to the river edge and place quadrats at intervals along and count the different species in each quadrat at each distance repeat for 2 more transects
• Which is an abiotic factor that could affect the number of different plant species found near a river


  moisture levels in the soil
• Increasing numbers of cows are being farmed across the world. Explain the environmental implications of increasing the numbers of cows being farmed.

  Cows produce methane during digestion, which is a greenhouse gas. Methane also contributes to global warming, intensifying the effects of climate change. Also land is often cleared to create pasture for cows. This leads to deforestation, which reduces biodiversity and decreases the ability of forests to absorb carbon dioxide.
• Which domain are sea lice classified in?


  eukaryota
• Some salmon have genes that result in fewer sea lice attaching to the skin. Describe how fish farmers can selectively breed salmon that sea lice cannot attach to.


  select fish that have no attachment of sea lice and breed selected fish together. Then select offspring that have the least sea lice and breed the selected offspring together and repeat over many generations until all offspring have no sea lice attached
• Explain the disadvantage of selectively breeding


  all the species are genetically similar therefore all of them may have the same inherited disorder
• Which hormones are given to women having IVF treatment


  FSH and LH
• Name the target organ of the hormones used for IVF


  ovaries
• Describe why microscopes are needed in the process of IVF


  to be able to select and check eggs
• Describe how the hormones given to women during IVF treatment interact with other hormones to prepare the body for pregnancy


  Hormones cause an increase in progesterone and oestrogen progesterone and oestrogen maintain the uterus lining and lining is prepared for the embryo to be inserted
• Give two arguments against the use of IVF treatment


  success rate is low and multiple births are a risk to the mother which are more likely with IVF
• Give one internal condition controlled by homeostasis


  blood glucose concentration and oxygen
• Explain why the control of body temperature is important.


  To maintain a temperature close to optimal conditions for enzyme action
• Which gland secretes hormones to stimulate the adrenal glands


  pituitary gland
• Explain the role of the adrenal glands in responding to a decrease in body temperature.


  adrenal glands release adrenaline to increase the heart rate of a person so a faster delivery of oxygen and glucose to the brain can help respiration which is needed to increase body temperature
• Explain how the thyroid gland controls the response to a decrease in body temperature by negative feedback


  A decreasing body temperature causes the thyroid gland to release thyroxine which increases metabolism so increasing body temperature decreases the release of thyroxine