paper 1 wrong Flashcards
explain why a bomb calorimeter gives a more accurate value than a normal energy reader
- because the system is sealed as it has a life
- there is less heat loss
- and the stirrer distributes the heat evenly
- and all of the food burns
The optimum pH of an enzyme is pH 6. Explain why this enzyme would not work at pH 10.
The enzyme denatures which changed the shape of the active site so the enzyme cannot form the enzyme-substrate complex.
Explain why antibiotics can be used to treat bacterial infections
They inhibit processes in bacteria. So bacteria are destroyed. But antibiotics do not damage the host cell.
Describe why a person with cataracts will see a blurry picture.
Protein had built up in the lens so the light is dispersed.
Describe how messages are sent from the brain to the muscles.
by electrical impulses along a motor neurone to the effector
Describe how stem cells produce the cells of an embryo
The stem cells divide by mitosis and then cells differentiate to become specialised cells
Discuss the benefits of using stem cells, that can be made from a patients own skin cells, to treat the patient
The embryos don’t need to be used so a donor is not needed. They can differentiate into any type of cell to replace damaged cells or tissue. They will match the tissue of the patient as there will be a less chance of rejection
Explain, using knowledge about natural selection, why rhing closely related could make bats susceptible to extinction.
All of the population of bats are genetically similar. If there is a selective pressure they will be susceptible to die as it is less likely there will be adapted bats to survive. So fewer bats will be able to reproduce and so the species can’t evolve
The genetic material of some plant virus is a single stranded RNA. Thw RNA is copied by the infected host cell and acts as a mRNA molecule. Describe how protein synthesis makes viral proteins from this mRNA.
Translation occurs. Then the mRNA goes to and binds to the ribosome. Each base triplet codes for one amino acid. The mRNA sequence determines the order of the amino acids. The tRNA has anticodons that are complementary to the codons. The tRNA transfers the amino acid. A peptide bond forms between amino acid so a polypeptide forms. The polypeptide folds into a viral protein.
Explain why potato cells do not burst when placed in water.
The potato cells havw a cell wall which provides support to the cell to make it turgid.
A patient has an overweight BMI but a healthy waist to hip ratio. Comment of this.
Suggests that fat isn not around viral organs or thst the patient may have high percentage of muscle.
A patient drinks more than the guidance of alcohol units. But they have never smoked a cigarettes. Comment on the health risks to this person.
They are consuming too much alcohol which affects the liver causing liver damage. They are not smoking which reduces the risk of cardiovascular disease or a stroke.
Describe how a mutation in the non coding region of a gene can lead to the production of less protein.
The RNA polymerase binds less well. So less mRNA is produced.
What is the cause of a protein folding incorrectly?
A mutation in the coding region of a gene changes the sequence of amino acids.
Does a mutation in the coding or the non coding region of a gene change the shape of a tRNA molecule?
None of them
Describe how base pairs are bonded together in a DNA molecule
They have weak hydrogen bonds between complementary bases A and T, C and G
A student wanted to extract DNA from fresh peas. Explain why enzyme protease was added to the mixture
Protease breaks down proteins in the nuclear membrane and also destroys enzymes that may break down the DNA.
A student wanted to extract DNA from peas. State why ice cold ethanol was poured into the filterate.
To precipitate the DNA as DNA is insoluble in ethanol
Explain why chlamydia can be treated with antibiotics
It is killed by antibiotics as chlamydia is caused by bacteria
Explain how HIV can lead to the onset of AIDS
HIV destroys white blood cells which weakens the immune system making the person more susceptible to other diseases.
A bacteria was discovered that was resistant to 26 antibiotics. Explain how this bacteria developed resistance to antibiotics.
There is variation in the bacteria population. By natural selection only the resistant bacteria survived the treatment by antibiotics. These resistant bacteria reproduce and their offspring inherit the resistance.
Describe the stages of antibiotic development that would occur after the discovery of a new antibiotic.
The antibiotics would go through a development phase. It would then go through a pre-clinical trials where the test on animals and then cells. Then it goes to clinical trials where they test on healthy volunteers and patients, double blind trials can also happen.
Some lipase was added to a test tube of milk to test the fat content. The pH of the mixture was 7. The test tube was placed in a water bath for 10 mins and the pH changed to 5. Explain what caused the change in pH.
Lipase breaks down fats into fatty acids and glycerol which are acidic that lowers the pH of the mixture.
Describe how a student could prepare a microscope slide to show mitosis in the growing roots of a garlic plant.
Use the root meristem. Soften the root with heat or alcohol. Crush the root onto the slide and stain the root wirh iodine. Add a drop of water to the slide and add a cover slip.
