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What is a pathogen?

A pathogen is a microorganism that causes a disease. Pathogens spread communicable diseases meaning that they are transmitted person to person and are infectious. Types of pathogens include bacteria, fungi, ...
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Answered by Francesca D. • Biology tutor
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What are the functions of the cell membrane?

The cell membrane separates the intracellular and extracellular environments. The lipid bilayer only allows small polar molecules (such as O2 or CO2), small hydrophobic molecules (fatty acids, steroid hormon...
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Answered by Francesca D. • Biology tutor
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How can bacteria become resistant to antibiotics and how can doctors reduce the number of bacteria that become resistant?

-A mutation in a pathogen may produce a new strain. This new strain may become resistant to an antibiotic through natural selection . The new strain may spread rapidly as the individual is not immune to it a...
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Answered by Helen C. • Biology tutor
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Using the Hardy Weinberg principle, calculate the frequency of the heterozygous genotype in the population if the frequency of the dominant allele p is 0.864. Express your answer as a percentage of the population.

p 2 + 2pq + q 2 = 1.0 p + q = 1.0 1.0 - p = q 1.0 - 0.864 = 0.136 q = 0.136 Frequency of heterozygous genotype = 2pq 2 x 0.864 x 0.136 = 0.235 As a percentage of the population- 23.5%
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Answered by Helen C. • Biology tutor
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Explain the difference between spatial and temporal summation at a synapse.

-Spatial summation occurs when multiple presynaptic neurones together release enough neurotransmitter (e.g. acetylcholine) to exceed the threshold of the postsynaptic neurone. For example, neurone A and neur...
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Answered by Helen C. • Biology tutor
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