Mock Practise Flashcards
Why doesnt all of the solar energy falling on the producers used to from biomass
• light is of the wrong wavelength for photosynthesis
• light is reflected
• energy loss due to respiration
When choosing a plate out of a range of dilutions what do you look for and why
• no clumping of colonies - avoid an underestimate
• avoid too few as it wouldn’t give an accurate estimate
A sample of the Staphylococcus was stained purple by the Gram stain technique.
Describe what the purple staining indicates about the structure of the bacterial cell wall.
• no lipoprotein layer
• thick peptidoglycan layer
• gram positive
Why is ATP described as an universal energy currency
Used by all organisms in most reactions
State a technique that shows the relatedness of two varieties of barnacles
DNA fingerprinting
Two possible causes of increased DNA mutation rate
UV rays
Chemical mutagen
State the function of the tapetum
Provide nutrients for pollen
Provide waterproof coat for pollen grains
Describe the function of the tube nucleus in the growth of the pollen tube
Controls the pollen tube
Controls the synthesis for hydrolytic enzymes
Describe the role of mitosis and meiosis in the formation of the female gamete
Megaspore undergoes meiosis
Forms 4 haploid nuclei
One of these undergoes 3 mitotic divisions
One of these nuclei becomes the oosphere
Why fertilisation in plants is referred to as double fertilisation
1 male nucleus fuses with oosphere to produce a diploid zygote
Second male nucleus fuses with polar nuclei to produce triploid endosperm nucleus
How would the appearance of a flower be different if the flower was wind-pollinated
Absent petals, not brightly coloured
Anthers hanging outside the flower
Feathery stigma that is exposed
State natural barriers to infection in the body
Skin - Skin flora (bacteria
Blood clotting - inlfammation
Stomach acid - low pH
Why is the body described as a host to other living organisms
Many organisms live in/on the human body
Explain how phagocytes and T lymphocytes bring about the cell-mediated response against a virus
• phagocytes carry out phagocytosis and engulf virus infected cell
• colonal expansion of T cells
• cytokines stimulate phagocytosis
• killer T cells cause cell lysis
Why can’t antibiotics kill viruses
Viruses dont have a cell wall nor a metabolism
