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12. (a) (i) A virus has been described as a piece of genetic material that has escaped from a cell - Leaving Cert Biology - Question 12 - 2013
Question 12
12. (a) (i) A virus has been described as a piece of genetic material that has escaped from a cell. Give one piece of evidence that supports this description. (ii)... show full transcript
Worked Solution & Example Answer:12. (a) (i) A virus has been described as a piece of genetic material that has escaped from a cell - Leaving Cert Biology - Question 12 - 2013
Step 1
Step 2
Explain why this is the case.
Answer
Viruses are obligate parasites because they can only replicate and reproduce inside a host cell. They require the cellular machinery of a host organism to synthesize their components and reproduce, as they lack the necessary structures for independent metabolism.
Step 3
Give an example of how a virus might be beneficial to mankind.
Answer
Viruses can be beneficial in various ways, such as through genetic engineering. For instance, certain viruses are used in gene therapy to treat genetic disorders by delivering corrective genes into patients' cells. Additionally, viruses are also utilized in vaccine production, which helps in controlling diseases.
Step 4
Step 5
Draw a large diagram of a bacterial cell to show: 1. The relative positions of the cell wall, cell membrane and capsule.
Answer
The diagram should include the following components: a cell wall that encapsulates the cell membrane, which in turn surrounds the cytoplasm. A capsule may be shown as an additional layer encompassing the outer surface of the cell wall.
Step 6
Step 7
Under what circumstances does a bacterial cell form an endospore?
Answer
A bacterial cell forms an endospore under harsh environmental conditions, such as extreme heat, desiccation, or when nutrients become scarce. This process ensures the survival of the bacteria in unfavorable conditions.
Step 8
Describe briefly how an endospore forms.
Answer
Endospore formation begins when the bacteria replicate their DNA and then encase one copy in a protective thick wall. This structure, known as the endospore, is formed inside the cell and can remain dormant until conditions become more favorable for growth.
Step 9
Step 10
Distinguish clearly between antibodies and antibiotics by writing a note about each.
Answer
Antibodies are proteins produced by the body in response to the presence of antigens, such as pathogens, to help neutralize or destroy them. Antibiotics, on the other hand, are substances produced by microorganisms that kill or inhibit the growth of other microorganisms, particularly bacteria, and do not affect viruses.
Step 11
In relation to antibodies, distinguish between active and passive immunity.
Answer
Active immunity occurs when the body produces its own antibodies in response to an infection or vaccination. Passive immunity involves the acquisition of antibodies from another source, such as from mother to child through breast milk or through antibody injections.
Step 12
Using your knowledge of antibiotics and bacteria, suggest why a person is more likely to pick up an infection in hospital than at home.
Answer
A person is more likely to pick up an infection in a hospital than at home due to the presence of antibiotic-resistant strains of bacteria in healthcare settings. Additionally, patients in hospitals may have compromised immune systems and less stringent hygiene practices, creating an environment conducive to the spread of infections.