2 Cells Flashcards
Knowledge based questions on cell structure, cell transport, osmosis, mitosis, the immune system and HIV.
Name the process by which prokaryotic cells divide. (1)
Binary fission.
Name two structures present in plant cells that are not present in animal cells. (1)
Any two of the four answers to get the mark
- Chloroplasts
- Cell wall
- Cell vacuole
- Starch grains
Cell fractionation Explain why the solution was ice-cold, buffered and isotonic. (3)
Ice-cold - Slows enzyme activity to prevent digestion of organelles.
Buffered - Maintains pH so that enzymes are not denatured.
Isotonic - Prevents osmosis so no shrinkage of organelles.
Cell fractionation Explain why the biologist used a blender and then filtered the mixture. (2)
The blender homogenises the cells. It is then filtered to remove larger debris.
Outline the role of organelles in the production, transport and release of proteins from eukaryotic cells. (4)
The DNA in the nucleus codes for specific proteins.
The ribosomes produce the proteins.
Mitochondria produce ATP used for protein synthesis.
The Golgi apparatus modifies and packages the proteins.
Give one advantage of viewing a biological specimen using a transmission electron microscope compared with using a scanning electron microscope. (1)
Higher resolution.
What is the function of the mitochondrion? (1)
Aerobic respiration.
The movement of sodium/Na ions out of the cell allows the absorption of glucose into the cell lining the ileum. Explain how. (2)
Movement of sodium out of the cell generates a concentration gradient for Na.
The Na moves into the cell lining the ileum by co-transport, bringing the glucose molecules with it.
Describe and explain two features you would expect to find in a cell specialised for absorption. (2)
Microvilli increases surface area for absorption.
Large number of carrier proteins which increase the rate of absorption.
Give two similarities in the movement of substances by diffusion and by osmosis. (2)
Diffusion and osmosis both move substances down a concentration, from high concentration to low concentration.
Both diffusion and osmosis are passive processes which do not use energy from respiration.
Explain the advantages of lipid droplet and micelle formation. (3)
The droplets increase surface area for enzyme action so hydrolysis happens faster.
Micelles carry fatty acids and glycerol through the membrane to the intestinal epithelial cell.
Explain how high absorption of salt leads to a build up of tissue fluid. (2)
Higher salt absorption results in lower water potential of the tissue fluid, so less water returns to the capillary by osmosis.
Give three properties of water that are important in biology. (3)
Water is a solvent.
Water has a relatively high specific heat capacity.
Water has cohesion.
Name the fixed position occupied by a gene on a DNA molecule. (1)
Locus/Loci
Describe how a gene is a code for the production of a polypeptide. Do not include information about transcription or translation in your answer. (3)
The base sequence of the gene is in triplets. This determines the sequence of amino acids in the polypeptide.
Mitosis is important in the life of an organism. Give two reasons why. (2)
Replaces damaged or dead cells.
Increase in cell number.
In which phase of the cell cycle does DNA replication take place? (1)
Interphase.
Describe the role of the spindle during mitosis. (2)
The spindle separates the chromosomes of a parent cell into two daughter cells.
Meiosis also occurs during the life cycle of organisms. What is the importance of meiosis? (2)
The chromosome number is halved by meiosis, which then ensures that during the new cell has a full number of chromosomes a fertilisation.
Describe how a phagocyte destroys a pathogen present in the blood. (3)
The phagocyte engulfs the pathogen, which forms a phagosome. This fuses with a lysosome which then releases hydrolitic enzymes which hydrolyse the pathogen.
Give two types of cell, other than a pathogen, that can stimulate an immune response. (2)
Abnormal cells
Antigen presenting cells
What is the role of the disulfide bridge in forming the quaternary structure of an antibody? (1)
The disulfide bridges join the different polypeptide chains together.
Determining the genome of viruses could help scientists develop a vaccine. Explain how. (2)
The scientists can identify the proteome. They could then identify the potential antigens to use in the vaccine.
What is a monoclonal antibody? (1)
Antibodies produced from cloned plasma cells.
Describe how HIV is replicated. (4)
Attachment proteins attach to receptors on the helper T cell.
RNA enters the cell where it is converted into DNA by reverse transcriptase. A viral protein is produced, and then the virus is assembled and released from the cell.
Describe how the human immunodeficiency virus (HIV) is replicated once inside helper T cells. (4)
The RNA is converted into DNA by reverse transcriptase. This DNA is inserted into the T helper cell’s nucleus. The DNA is transcribed into HIV mRNA, where it is then translated into HIV proteins for assembly and release into viral particles.
