Questions Flashcards
DNA codes for proteins within the cell
Some regions of DNA are described as non coding
Explain why some regions of DNA can be described as non coding
It is not present in the mature mRNA
It is not translated
Non coding regions of DNA show more variation than coding regions
Suggest why non coding regions of DNA show more variation
Doesn’t affect survival
What is the basis of classification called
Phylogeny
Suggest how the increase in biomass over time in a plant could be determined experimentally
Measure changes in dry mass over time
Outline the process of primary succession and explain what deflected succession is. (6)
Primary succession is a slow process, go through seral stages.
- Begins with pioneer community
These species arrive as seeds or spores. They have certain adaptations such as the ability to produce large amount of seeds, tolerate extreme environments, have a low biomass. - Immediate community
weathering of bare rock and humus (decomposed pioneer species) produce basis of the soil.
Herb species are grown, including grass
Followed by shrubs and trees - Climax community
It is in a stable state and little change over time
Few dominant species and plants dependent on climate
Deflected succession is when human activities has caused harm and prevented the ecosystem from reaching climax community. Therefore plagioclimax is formed where the final stage is stopped artificially
Suggest and explain why a low pH might cause the red pigment to leak out of the beetroot cells.
A low pH denatures membrane and increases the permeability causing pigment to leak
Outline the way in which Wallace contributed to the acceptance of Darwin’s theory of natural selection by the wider scientific community
Similar ideas to Darwin
Published paper together
Describe the stages of mitosis ( 6 marks)
Prophase
Chromosomes condense
Nuclear envelope and nucleolus has disappeared
Centriole move to the poles
Metaphase
Chromosomes line up at the equator
Spindle fibres form
Anaphase
Spindle fibres are shortening
chromatids are separating and are being pulled to opposite sides of the cell
Telophase
Chromatids have been pulled to opposite sides of the cell
A new cell membrane is visible
Cytokinesis is beginning to divide
In one tissue, the scientists found a genetic mutation that stopped the metaphase checkpoint from working
suggest an abnormality that scientists might observe in the cells of this tissue
incorrect number of chromosome
Scientists observed cells with chromosomes that had been replicated despite containing damaged DNA.
Suggest which cell cycle checkpoint is no longer working in this tissue and justify your answer.
G1 Checkpoint
DNA damage is checked
Describe two differences between how DNA is separated during binary fission (bacteria) and mitosis
No lining of chromosomes across equator in binary fission
No spindle fibres
Callose is formed by beta glucose monomers
Describe the difference between the structures of callose and cellulose
Cellulose is not branched
Cellulose has 1,4 glycosidic bonds
What are the features of amylose
Amylose is insoluble
It is unbranched
It is formed by condensation reaction
Describe two ways in which the structure of mitochondrial membrane is related to the function of the mitochondrion
Allow formation of H+ ions
Outer membrane is highly permeable to allow movement of molecules
