AS Exam Questions Flashcards
(18 cards)
Name the type of bond between:
Complementary base pairs
And
Adjacent nucleotides in a DNA strand
Complementary base pairs- hydrogen bonds
Adjacent nucleotides in a DNA strand- ester bonds
Describe 2 differences between the structure of a tRNA molecule and the structure of an mRNA molecule.
- tRNA has hydrogen bonds, mRNA does not.
- tRNA is ‘cover leaf shape’, mRNA is linear
In a eukaryotic cell, the structure of the mRNA used in translation is different from the structure of the pre-mRNA produced by transcription.
Describe and explain a difference in the structure of these mRNA molecules.
- mRNA has fewer nucleotides than pre-mRNA which has more.
- Because of splicing
Describe how HIV is replicated.
- Attachment proteins attach to receptors on helper T cells.
- RNA enters cell
- Reverse transcriptase converts RNA to DNA
- Viral protein is produced
- Virus particles assembled and released from cell.
U. marinum cells ingest bacteria and digest them in the cytoplasm.
Describe the role of one named organelle in digesting these bacteria.
- Lysosomes
- Fuse with vesicles
- Releases hydrolytic enzymes
Use your knowledge of surface area to volume ratio to suggest an explanation for the position of mitochondria in large U. marinum cells.
- Larger cells have smaller surface area to volume area.
- Takes longer for oxygen to diffuse to mitochondria.
Describe and explain the arrangement of the genetic material during prophase.
- Chromosomes are becoming visible
- Because still condensing
Name the fixed position occupied by a gene on a DNA molecule.
Locus
Describe how a gene is a code for the production of a polypeptide. Do not include information about transcription or translation in your answer.
Base/nucleotide sequence in triplets, determines order of amino acid sequence in polypeptide.
Describe how the structure of glycogen is related to it’s function.
- Helix is coiled so compact
- Polymer of glucose so easily hydrolysed
- Branched so more ends for faster hydrolysis
- Glucose polymer so provides respiratory substrate for energy release.
- Insoluble so no easily lost from cell.
Give the pathway a red blood cell takes when travelling in the human circulatory system from a kidney to the lungs.
- Renal vein
- Vena cava to right atrium
- Right ventricle to pulmonary artery
Tissue fluid is formed from blood at the arteriole end of a capillary bed. Explain how water from tissue fluid is returned to the circulatory system.
- Plasma proteins remain
- creates a water potential gradient
- Water moves to blood by osmosis
- Returns to blood by lymphatic system.
Suggest and explain an advantage of carrying out an investigation at 30 degrees rather than 20.
-Warmer water has more kinetic energy
- Quicker osmosis
Kidney cells produce a glycoprotein called erythropoietin. Identify 2 organelles in kidney cells that enable the production of EPO.
- Ribosomes
- Golgi apparatus
Explain the biological advantage to athletes of injecting synthetic EPO.
- More red blood cells
- More aerobic respiration/ ATP produced so exercise harder.
Describe how mice injected with human EPO produce anti-human EPO antibody.
- Human EPO/ antigen displayed on antigen presenting cells/ B cells.
- Specific helper T cells stimulates B cell to divide.
- Plasma cells secrete antibody.
Describe the roles of anti-human EPO antibody and anti-mouse antibody with enzyme attached in producing a positive result for EPO in the ELISA test.
Role of anti-human EPO antibody- attaches to EPO in plastic well
Role of anti-mouse antibody with enzyme attached- attaches to anti-human antibody.
Substrate is added, enzyme causes colour change, product is a positive result.
Some people object to using monoclonal antibodies in testing programmes. Suggest why.
Welfare issues with using mice/animals.
