Biology

Biology Related

Review Biology related questions and content

AIDS is caused by what type of infectious agent?

  • A. Protist.
  • B. Bacterium.
  • C. Insect.
  • D. Virus.
Correct Answer: D

Rationale: The correct answer is D: Virus. AIDS is caused by the Human Immunodeficiency Virus (HIV), which attacks the immune system and weakens the body's ability to fight infections. Viruses are unique infectious agents that require a host cell to replicate and cause disease, which is the case with HIV.

A: Protists are eukaryotic organisms like parasites, but they are not known to cause AIDS.
B: Bacteria are prokaryotic organisms that can cause various infections, but they do not cause AIDS.
C: Insects are not infectious agents themselves but can transmit diseases, they do not cause AIDS.

In summary, the correct answer is D because HIV, a virus, specifically causes AIDS by targeting and damaging the immune system.

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Which of the following is a protein?

  • A. cellulose
  • B. hemoglobin
  • C. estrogen
  • D. ATP
Correct Answer: B

Rationale: Hemoglobin is the correct answer as it is a protein. Proteins are large, complex molecules composed of amino acids that are essential for various structural and functional roles in the body. Hemoglobin, specifically, is a protein found in red blood cells and is responsible for carrying oxygen from the lungs to different parts of the body, highlighting its crucial role in oxygen transportation.

The aerodynamic nature of a bird's wing is an example of what central theme in biology?

  • A. Heredity.
  • B. Ontogeny.
  • C. Organisms and their environment.
  • D. Structure and function.
Correct Answer: D

Rationale:

The structure of a bacteria is circular. Which bacteria fits this criteria?

  • A. Mycobacterium.
  • B. Actinomyces.
  • C. Clostridium.
  • D. Neisseria.
Correct Answer: C

Rationale: Rationale:
1. The correct answer is C: Clostridium.
2. Clostridium is a type of bacteria that has a circular structure known as a plasmid.
3. Plasmids are small, circular DNA molecules found in bacteria.
4. Mycobacterium (A) has a rod-shaped structure with a linear chromosome.
5. Actinomyces (B) has a filamentous structure, not circular.
6. Neisseria (D) has a diplococci shape, not circular.
In summary, Clostridium fits the criteria of having a circular structure due to its plasmid, making it the correct choice.

Which cellular component contributes to the protection, communication, and passage of substances into and out of the cell?

  • A. Nucleus
  • B. Cell membrane
  • C. Endoplasmic reticulum
  • D. Cytoplasm
Correct Answer: B

Rationale: The cell membrane is responsible for protecting the cell, facilitating communication with the external environment, and controlling the passage of substances into and out of the cell. It acts as a barrier, regulating the entry and exit of molecules to maintain the cell's internal environment. The nucleus, endoplasmic reticulum, and cytoplasm have their own distinct functions within the cell but do not primarily serve the purposes mentioned in the question.

Which option demonstrates complementary base pairing in DNA?

  • A. A and G
  • B. A and C
  • C. A and A
  • D. A and T
Correct Answer: D

Rationale: In DNA, adenine (A) pairs with thymine (T) and cytosine (C) pairs with guanine (G). This is known as complementary base pairing. Adenine always pairs with thymine via two hydrogen bonds, forming a strong bond essential for DNA structure and replication. Therefore, the correct option that demonstrates complementary base pairing in DNA is A and T (D). This pairing is crucial during DNA replication and ensures the accurate transmission of genetic information.

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