Thursday, 9 May 2013

Unit 1 quiz & answers

Unit 1 AS biology quiz  Answers - Miss Timms

1.      What kind of bond links amino acids together? Peptide bond.
2.      What type of reaction is involved in linking amino acids together? Condensation reaction
3.      What four different components make up an amino acid? Amino group, carboxyl group, r group and hydrogen atom.
4.      What is a catalyst? Catalysts alter the rate of a chemical reaction without undergoing permanent changes.
5.      Why are enzymes effective in tiny quantities? They can be reused repeatedly and are therefore effective in small quantities.
6.      Explain why enzymes function less well at lower temperatures? A reduction in temperature leads to a reduction in kinetic energy of the molecules within the reaction, so less collision occur and the reaction is slower.
7.      Why is the electron microscope able to resolve objects better than the light microscope? As the electron beam has a shorter wavelength than light.
8.      In which process are ribosomes important? Protein synthesis
9.      What is the overall function of the cell-surface membrane? It forms a boundary between the cell cytoplasm and the environment, allowing different condition to be established inside the cell compared to outside.
10.  What is the name of the blood vessel that supplies the heart muscle with oxygenated blood? Coronary arteries.
11.  List the correct sequence of the four main blood vessels and four heart chambers that a red blood cell passes through on its journey from the lungs, through the heart and body, and back again to the lungs? Pulmonary vein, left atria, left ventricle, aorta, superior and inferior vena cava, right atria, right ventricle and pulmonary artery.
12.  Indicate whether each of the following statements are true or false?
a.       The left and right ventricles contract together? True
b.      Heart muscle is myogenic? False (only in SAN and AVN)
c.       Semi-lunar valves occur between the atria and ventricles? False
d.      The wave of electrical activity from the atrioventricular node is conveyed along the bundle of His? True
e.       The wave of electrical activity from the sinoatrial node directly causes the ventricles to contract? False
13.  What is an antigen? Any part of an organism or substance that is recognised as non-self (foreign) by the immune system and stimulates an immune response.
14.  State two differences between T cells and B cells?
B cells
T cells
·         Matures in bone marrow
·         Matures in thymus gland
·         Involved in humoral immunity
·         Involved in cell-mediated immunity
·         Responds to foreign material outside body cells
·         Responds to foreign material inside body cells
·         Responds to bacteria and viruses
·         Responds to own cells altered by viruses or cancer and to transplanted tissues
15.  Explain how high temperatures (above 60 degrees) may completely prevent enzymes from functioning? Denaturation (protein unfolding and aggregation) may occur which is the permanent change of an enzyme no longer allowing it to function.
16.   Why do specimens have to be kept in a near-vacuum in order to be viewed effectively using an electron microscope? Because electrons are absorbed by the molecules in air.
17.  Name the organelle that is being referred to in each of the following descriptions?
a.       It possesses structures called cristae? Mitochondria.
b.      It contains chromatin? Nucleus.
c.       It synthesises glycoproteins? Golgi apparatus.
d.      It digests worn out organnells? Lysosomes.

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