P2 - 2018 Flashcards
Which plant structure fits this statement:
Has stacked membranes arranged in parallel and contains DNA
chloroplast
Which plant structure fits this statement:
Is made of polysaccharide
cell wall
Which plant structure fits this statement:
Is an organelle and is not surrounded by two membranes
Golgi apparatus
Human breast milk is produced + secreted by gland cells which have adaptations that include many mitochondria and many Golgi vesicles.
The milk contains a high concentration of protein.
Explain the role of these cell adaptations in the production and secretion of breast milk
Many mitochondria release energy for synthesis of protein
Many Golgi vesicles transport protein to cell membrane
Describe how a peptide bond is formed between two amino acids to form a dipeptide
Condensation reaction (a loss of water) Between COOH
The secondary structure of a polypeptide is produced by bonds between amino acids.
Describe how
Hydrogen bonds Between NH group of one amino acid and C=O group
Two proteins have the same number and type of amino acids but different tertiary structures
Explain why
Different sequence of amino acids
Forms ionic bonds in different places
Describe the relationship between size and surface area to volume ratio of Explain why oxygen uptake is a measure of metabolic rate in organisms
As size increases, ratio of surface area to volume decreases
Explain why oxygen uptake is a measure of metabolic rate in organisms
Oxygen used in respiration which provides energy
The scientist used units of μmol g−1 h−1 for the rate of oxygen uptake.
Suggest why he used μmol in these units
Measures small volume of oxygen uptake
The scientist used the ratio of surface area to mass, rather than the ratio of surface area to volume.
Suggest 1 practical advantage of measuring the masses of frog eggs, tadpoles and
adults, compared with measuring their volumes.
more accurate in measuring mass
or
Causes less damage to animal to measure mass
Give two similarities in the movement of substances by diffusion and by osmosis
Movement from high concentration to low concentration
not active processes
What is the name given to the division of cytoplasm during the cell cycle?
Cytokinesis
Describe + explain what a student should do when counting cells to make
Binary fission Cytokinesis Phagocytosis Segregation
sure that the mitotic index he obtained for this root tip was accurate
Repeat count to ensure figures are correct
What is digestion?
Hydrolysis of large substances to smaller soluble substances
Endocellulases and exocellulases act at different places on cellulose molecules
Suggest why
Active sites are different shapes so different enzyme-substrate complexes are formed
The scientist used the same concentration of endocellulase and exocellulase in the mixtures. The rate of digestion of cellulose is greatest when both enzymes are present.
Suggest why.
Endocellulase increases surface area for exocellulase to digest
What is the equation for calculating the percentage loss in mass?
initial Mass − Final Mass
———————————– x100
Initial Mass
Suggest and explain one reason why bacteria resistant to tetracycline are more
common than bacteria resistant to streptomycin in these farm animals.
Tetracycline used in higher doses making resistant bacteria more likely to pass on gene for resistance
In recent years, these farm animals have not been given tetracycline in their food. Despite this, the percentage of bacteria resistant to tetracycline has remained constant
why?
Bacteria pass on resistance gene when they reproduce
Compare and contrast the DNA in eukaryotic cells with the DNA in prokaryotic cells
(5)
(2 compare, 3 contrast)
- Nucleotide structure is identical
- Nucleotides joined by phosphodiester bond
- DNA in mitochondria have similar structure to DNA in prokaryotes
- Eukaryotic DNA is longer
- Eukaryotic DNA is linear, prokaryotic DNA is
circular
Haemoglobins are chemically similar molecules found in many different species.
Differences in the primary structure of haemoglobin molecules can provide evidence of phylogenetic (evolutionary) relationships between species.
Explain how
(5)
- Mutations change nucleotide sequence
- Causing change in amino acid sequence
- Mutations build up over time
- More mutations in nucleotide sequence between distantly related species
- Distantly related species have earlier common ancestor
