Jan 2021 Flashcards
1.4. An electron microscope was used for viewing a cell. Give 2 reasons for using an electron microscope instead of a light microscope. (2)
(1) Magnification is greater
(2) Resolution is greater
1.5. What is the function of the Golgi apparatus? (1)
packing / export of enzymes / hormones to be
released from the cell
2.4. Using immunological differences, explain why the chimpanzee albumin produces a less dense precipitate than the Species X albumin when added to the anti-Species X albumin antibodies. (2)
(1) Chimpanzee albumin is different shape / structure / sequence of amino acids to Species X albumin
(2) (Anti-species X albumin) antibodies specific / complementary to species X albumin / less binding to chimpanzee albumin
3.3. Describe the role of tRNA in the process of translation. (3)
(1) Each carries a specific amino acid
(2) Anti-codon complementary / binds to mRNA codon
(3) Allows (ribosomes to) link amino acids by peptide bonds
4.1. Explain why the process of DNA replication is described as semi-conservative. (2)
(1) Retains one original strand
(2) New strand formed by complementary base pairing OR original strand acts as template
4.2. Describe how the DNA is isolated from the bacteria. (2)
(1) Bacterial cells broken open
(2) Contents of cells spun at high / suitable speed
5.2. Define isomer. (1)
(molecules with) same empirical / chemical formula but different structural formula
6.2. Suggest why the students wash the glass tube with distilled water & why they dry it thoroughly between each set of readings. (2)
(1) (Washing) To remove contamination / residue from previous solutions
(2) (Drying) Avoid dilution of next mixture
7.1. Describe the structure of sucrose. (2)
(1) Glucose and fructose molecules
(2) Joined by a glycosidic bond
7.7. Describe a biochemical test for fat. Include the positive result for this test. (2)
(1) (Mix/shake sample) with ethanol, then water OR add ethanol/alcohol and shake/mix then pour into/add water
(2) White/milky (emulsion)
