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Describe and explain the adaptions of leaves that maximise gas exchange (dont refer to organelles in your answers)

• many stomata

• Stomata allow gas diffusion

• Air spaces in the mesophyll

• Large surface area of cells for rapid diffusion

• Large leaf surface area to volume ratio So increases diffusion rate

Describe the roles of ribosomes, tRNA and ATP in the process of translation

• ribosomes bind to the start codon of the mRNA strand

• Ribosomes reads the mRNA and a tRNA molecule with anticodon complementary to the mRNA codons bring a specific AA

• Each tRNA molecule is bound to a specific amino acid

• A peptide bond forms between adjacent amino acids due to the energy released during ATP hydrolysis, this continues until the stop codon is reached

• The tRNA codon then dissociates from the amino acids to be reused

The scientist determines that the r/s value bewteen plasmid length and mean plasmid copy number for all 11 types of plasmids is -0.94

-0.94 is closer to -1 than 0 so is a strong significant correlation

Strains of bacteria with antibiotic resistance are more common in hospital use your knowledge of selection to explain why

• hospitals use high and frequent doses of antibiotics, or r long periods of time

• So resistant bacteria readily spread

• Bacteria with resistant allel survive reproduce and pass on alllele

• So resistant allele frequency increases / number of bacteria with resistant allele increases

A mutation can produce a gamete with one extr chromosome

Name the type of mutation that produces a gamete with one extra chromosome. Explain how meiosis can produce a gamete with one extra chromosome

Non disjunction

• where homologous chromosome are separated

• Because both chromosomes/ chromatids pulled to one pole

Figure 3 shows the dissociation curve fro oxyhaemaglobin in a species of crab at two temperautur’s.

Crabs use gills for gas exchange

Use the figure to explain how the increase in temperature affects the ability of haemocyanin to load or unload oxygen at the gills and tissues

• at lower temperatures haemocyanin has hihger affinity for oxygen at low partial pressures of O2

• At high pO2 in gills temperature change has no affect on O2

Explain how a change in the expression of genes coding from the carrier proteins can increase the rate of ripening of pears

• Increased gene expression produces more carrier proteins

• So more active transport of H+

Name structures that are found in some prokaryotic cells but rent found in all prokaryotic cells

• flagella

• Plasmids

• Capsid

• Pilli

What biological molecules do glycogen contain and how is it formed

• glucose

• Formed by condensation reaction and is a polymer

What biological molecules do sucrose contain and how is it formed

• glucose

• Fructose

• Formed in a condensation reaction

What biological molecules does DNA contain and how is it formed

• phosphate

• Condensation reaction

• Polymer