Biology P1 key knowledge

• What is the structure of DNA?

  Made of lots of repeating nucleotides which consist of a sugar, a phosphate and one of the four bases.
• What does the backbone of DNA consist of?

  The sugar and phosphate groups
• What chromosomes do males and females have?

  Males have XY

  Females have XX
• What is a phenotype?

  The characteristics an organism displays.
• Examples of genetic and environmental variation:

  Height (determined by genes but on if given the correct amount of food) Intelligence and Health (due to lifestyle factors)
• What is a mutation?

  Random change in the base sequence of an organism's DNA which leads to changes in the protein that it codes for.
• What is a motor neurone?

  Carries electrical impulses from the CNS to the effectors.
• What is a relay neurone?

  Carries and electrical impulse from the sensory neurone to the motor neurone.
• What is a sensory neurone?

  Carries information as an electrical impulse from the receptor to the CNS.
• What is selective breeding?

  When humans artificially select the plants or animals that are going to breed so that the genes for a desirable characteristic remain in the population.
• What is genetic engineering?

  Transfer a gene from one organism's genome to anothers genome in order to introduce a desirable characteristic.
• What are the symptoms of TB and how can we reduce the spread?

  Symtoms are coughing and lung damage and we can reduce the spread by those who are infected practicing good hygiene and avoiding crowded areas.
• What are the symptoms of cholera and how can we reduce the spread?

  Symptoms are diarrhoea leading to severe dehydration and we can reduce the spread by making sure everybody has access to clean water.
• What are the symptoms of chalara ash dieback and how can we reduce the spread?

  Symptoms are loss of leaves and lesions and we can reduce the spread by having restrictions on the movement of ash trees.
• What are the symptoms of malaria and how can we reduce the spread?

  Symptoms are fever and damage to red blood cells and we can reduce the spread by stopping mosquitoes from breeding or people can get protection from bites.
• What are the symptoms of chlamidya and how can we reduce the spread?

  There are no symptoms except infertility and we can reduce the spread by wearing condoms, reducing intercourse and screening.
• What are the symptoms of HIV and how can wer reduce the spread?

  Usually flu-like symptoms or none until several years later where it can lead to AIDS and we can reduce the spread by wearing a condom and not sharing needles.
• What is the food test for sugars and how do you carry it out?

  To test for reducing sugars you use the Benedicts test whereby you transfer 5cm of food solution to test tube and prepare a water bath and add 10 drops of Benedicts solution. Then place in water bath for 5 mins.
• What colour will a solution turn if it contains reducing sugars?

  It will go from blue to brick red.
• What is the test for starch and how do you carry it out?

  To test for starch we use the iodine test whereby 5cm of food solution is put in a test tube along with a few drops of iodine solution, then give the test tube a shake.
• What colour will a solution turn if starch is present?

  It will turn from orange to blue-black.
• What is the test for protein and how do we carry this out?

  To test for proteins we use the biuret test whereby you add 2cm of food solution to a test tube and add potassium hydroxide and copper sulfate, then give the test tube a shake.
• What colour will a solution turn if it contains protein?

  It will turn from blue to pink/purple.
• What is the test for lipids and how do we carry this out?

  To test for lipids we carry out the emulsion test whereby you take the food solution in a test tube and add 2cm of ethanol and shake it vigourously, then add 2cm of distilled water.
• What colour will a solution turn if it contains lipids?

  It will turn cloudy white.
• How do we carry out the practical of the effect of pH on amylase?

  Firstly place 1 drop of iodine in each spotting well, then set up 3 test tubes with 2cm of starch, 2cm of amylase and 2cm of pH 5 buffer. Then place them in a water bath for 10 mins and mix solutions into 1 test tube. After that place them back in water bath and start a stopwatch whereby every 30secs remove 1 drop of it and put in spotting well and continue until solution turns orange.