2020

• DNA molecule


  yh

  
• structure of DNA molecule

  2 strands that are coiled into a double helix structure
• A gene codes for a particular sequence of amino acids


  This sequence makes a specific protein
• D- Genome

  All of the genetic material of an organism
• which important scientific advance was made using knowledge of the human genome

  tracing how Aboriginal people spread across Australia.
• Which scientific term describes differences in characteristics btw individuals of a species

  Variation
• suggest why there might be an increasing number of snails similar to snail P in each future generation

  Better camouflaged so less likely to be eaten and will breed more.
• biodiversity

  the variety of all the different species in an ecosystem
• one use of peat taken from peat bogs

  used as fertiliser
• Why is the use of peat harmful to the environment

  The decay of peat releases carbon dioxide into the atmosphere, which increases global warming.
• cell division by meiosis

  -Four daughter cells are formed

  -The parent cell divides twice
• label 


  yesssssss

  
• fill 


  the blank

  
• Archae

  The domain does primitive anaerobic bacteria belong to
• Describe how the stimulus from the hot pan reaches the muscle in the arm.[4 marks]

  A:The stimulus is detected by receptors in the fingers which initiates an electrical impulse.The impulse travels via the sensory neurones, relay neurones then motor neurones to the effector which is the arm muscles.The impulse causes the muscle to contract and the hand to be pulled away from the hot pan.Between neurones, the impulse crosses gaps/synapses as chemical neurotransmitter.
• Q: A student investigated whether using the right hand or the left hand had an effect on reaction time.The student only tested right-handed people.Describe a method for the student’s investigation.Include details of the test you would use for reaction time.[4 marks]

  A:Select at least 3 people, the more the better.Perform a reaction time test at least 3 times using their right hand, such as pressing a buzzer when an audio or visual stimulus is given.Find the mean for each person and repeat the experiment using their left hands.Compare the means to find correlation between reaction time and hand used.It is important to choose participants of the same age & gender and perform the experiment at the same time of day.
• Q: Most of the world’s production of antibiotics is used in farming.Antibiotics are given to animals to prevent the spread of disease.Explain how the widespread use of antibiotics in farming is a threat to human life.[4 marks]

  A:The antibiotics given to the animals are passed into the environment in animal sewage which can flow into rivers. This causes bacteria both on land and in water to become resistant to the antibiotics.Some of these bacteria are human pathogens and cause human diseases. Due to the antibiotic resistance of the bacteria, humans will no longer be able to be treated and cured with the antibiotic.
• Q1: Suggest two advantages for garden centres of growing geraniums by asexual reproduction compared with sexual reproduction.[2 marks]

  A1:

  1. Only requires one parent plant.
  2. Will produce many genetically identical plants.

  Q2: Suggest two disadvantages for garden centres of growing geraniums by asexual reproduction compared with sexual reproduction.[2 marks]

  A2:

  1. They will be genetically identical so will all be susceptible to the same diseases.
  2. There will be no genetic variety for new colours & other characteristics to offer customers.
• Method 1:

  • Normal pregnancy via sexual intercourse
  • After 10 weeks, fluid from uterus is taken using a needle
  • The DNA of embryo is tested for cystic fibrosis (CF)
  • Free through specialist hospitals
  • Small risk of miscarriage

  Method 2:

  • IVF (In Vitro Fertilisation) is used to create embryos
  • All embryos are tested for CF
  • Only unaffected ones are implanted
  • IVF success rate is low (30% for women under 35 in 2017)
  • IVF is stressful and invasive
  • Not free on NHS for everyone

  🧠 Question 0 5 . 4

  Q: Suggest three reasons for choosing Method 1 instead of Method 2.[3 marks]

  A (your answer):

  1. Doesn’t need IVF which is stressful.
  2. The test is freely available.
  3. Test can be carried out even if the mother is pregnant.

  ✅ Question 0 5 . 5

  Q: Suggest one advantage of Method 2.[1 mark]

  A (your answer):

  • Child will definitely not have CF.
• Describe the reasons why deforestation takes place and the effects deforestation has on the environment.[6 marks]

  ✅ Answer:

  Tropical rainforests are cleared for land.This land is used to raise cattle, plant rice and other crops such as coffee and grow biofuels such as palm oil.Forests can also be chopped down to clear area for mining and collecting wood for use in building and paper.

  This whole process increases the amount of carbon dioxide in the atmosphere because there is less trees to take in the carbon dioxide, more respiration by microorganisms decaying the material (so releasing CO₂) and burning of the waste also releases CO₂.

  The build-up of CO₂ leads to global warming.Other consequences include habitat loss which lead to reduced biodiversity and soil erosion.
• Question 07.2

  Describe one way forests being called ‘The lungs of the planet’ can be considered to be a correct statement.[1 mark]

  ✅ Answer:Forests involve gas exchange with the atmosphere.

  🧾 Question 07.3

  Describe one other way forests being called ‘The lungs of the planet’ is an incorrect statement.[1 mark]

  ✅ Answer:In forests, CO₂ is used and oxygen is released, but in lungs, oxygen is used and CO₂ is released.