A-level Biology Specimen Paper: Topics in Cell Biology and Biochemistry, Exams of Biology

Download A-level Biology Specimen Paper: Topics in Cell Biology and Biochemistry and more Exams Biology in PDF only on Docsity! A-level paper 1 set 2 specimen paper Name what molecule formed when two molecules of glycine (amino acids) are joined together - water Why are no organelles visible in the cytoplasm of a red blood cell? - the cytoplasm is filled with haemoglobin Before a cell was examined using an electron microscope, it was stained. This stain causes parts of the structure of the cell -surface membrane to appear as two dark lines. Suggest an explanation for the appearance of the cell-surface membrane as two dark lines. - -membrane has phospholipid bilayer -stain binds to phosphate >on inside and outside of membrane Describe how substances move across cell-surface membranes by facilitated diffusion - -from a high to low concentration -using carrier proteins -the substances are protein specific An advantage of asexual reproduction - fewer stages so quicker An advantage of sexual reproduction - increases genetic diversity >so greater chance of survival *line shows steady increase and levels off* Explain the results without inhibitor (curve A) - -increases because more enzyme-substrate complexes formed -levels off because all enzyme molecules are involved in enzyme substrate complexes Explain why the reaction with a competitive inhibitor is faster than a reaction with a non-competitive inhibitor -when substrate concentration is varied - -competitive inhibitor doesn't cause change in shape of active site >so with competitive inhibitor, at high substrate concentrations (active) enzyme still available but with non-competitive inhibitor (active) enzymes no longer available -at higher substrate concentrations, the likelihood of enzyme-substrate collisions increases >this is not possible with a non-competitive inhibitor Scientists decided to collect animals from the soil samples for 40 minutes. Suggest how the scientists decided that 40 minutes was an appropriate time. - they repeat soil sorting for different times 6) memory cells produce antibodies faster Contrast the structure of a bacterial cell and the structure of a human cell - -bacterial cells much smaller than a human cell -bacterial cell lacks a nucleus, but a human cell does not -bacteial cell lacks membrane-bound organelles but human cell has membrane-bound organelles -bacterial ribosomes are smaller than human ribosomes (they have 70s, humans have 80s) -bacterial DNA is circular, human DNA is linear -bacterial DNA os 'naked' whereas human DNA is bound to histones Alpha glucose structure - Beta glucose structure - Amino acid structure - How many nanometers in 1 micrometer? - 1000 Why should you firmly squash a root tip? - To make the tissue layer thin >to allow light through