1. In plant cells, what structure provides rigidity and support?

A. Cell membrane
B. Golgi apparatus
C. Plastid
D. Cell wall

Correct answer: D

Rationale: The correct answer is D: Cell wall. The cell wall is a rigid structure found in plant cells that provides support and protection. It is composed of cellulose and other materials, forming a tough outer layer that helps maintain the cell's shape and prevents it from bursting under pressure. The cell membrane (option A) is a semi-permeable barrier that surrounds the cell but does not provide rigidity. The Golgi apparatus (option B) is involved in sorting and packaging proteins. Plastids (option C) are organelles responsible for functions like photosynthesis and storage, but they do not provide rigidity and support like the cell wall does.

2. What is the difference between active and passive immunity?

A. Active immunity is short-lived, while passive immunity is long-lasting.
B. Active immunity involves the body's own immune response, while passive immunity provides immediate protection through antibodies from another source.
C. Active immunity only protects against bacterial infections, while passive immunity works against both bacteria and viruses.
D. Passive immunity requires repeated vaccinations, while active immunity is a one-time process.

Correct answer: A

Rationale: The correct answer is A: "Active immunity involves the body's own immune response, while passive immunity provides immediate protection through antibodies from another source." Active immunity is long-lasting because it involves the body's immune system producing memory cells that remember specific pathogens, providing long-term protection. Passive immunity, on the other hand, is short-lived as it involves receiving pre-formed antibodies from an external source, such as through maternal transfer or injection of antibodies, which do not create memory cells for long-lasting protection.

3. Which word best synonyms with the word "elated"?

A. Angry
B. Sad
C. Excited
D. Confused

Correct answer: C

Rationale: "Elated" and "excited" both convey feelings of happiness and enthusiasm.

4. The neutral theory of molecular evolution proposes that:

A. Most mutations in DNA are selectively neutral and do not affect an organism's fitness.
B. All mutations are beneficial and contribute to the adaptation of a population.
C. The rate of evolution is primarily driven by strong directional selection pressures.
D. Genetic drift plays a negligible role in shaping genetic variation within populations.

Correct answer: A

Rationale: Rationale: A) The neutral theory of molecular evolution, proposed by Motoo Kimura in the 1960s, suggests that the majority of mutations that occur in DNA are selectively neutral, meaning they do not have a significant impact on an organism's fitness. These neutral mutations are not subject to natural selection and are allowed to accumulate in populations over time. This theory helps explain the high levels of genetic variation observed within populations. B) Option B is incorrect because not all mutations are beneficial. Mutations can be neutral, harmful, or beneficial, and the neutral theory specifically focuses on the idea that many mutations are neutral in their effects. C) Option C is incorrect because the neutral theory suggests that evolution is not primarily driven by strong directional selection pressures. Instead, it emphasizes the role of genetic drift and the accumulation of neutral mutations in shaping genetic variation. D) Option D is incorrect because

5. What property of a wave is responsible for determining its energy?

A. Amplitude
B. Wavelength
C. Frequency
D. Velocity

Correct answer: a

Rationale: The amplitude of a wave determines its energy, with higher amplitudes corresponding to higher energy levels.

6. What is the name of the regulatory region in a gene that controls its expression?

A. Exon
B. Intron
C. Promoter
D. Enhancer

Correct answer: C

Rationale: Rationale: A) Exon: Exons are the coding regions of a gene that are transcribed into mRNA and eventually translated into proteins. Exons do not regulate gene expression. B) Intron: Introns are non-coding regions of a gene that are removed during RNA processing and do not play a direct role in controlling gene expression. C) Promoter: The promoter is a regulatory region located at the beginning of a gene that initiates the process of transcription by binding transcription factors and RNA polymerase. It plays a crucial role in controlling gene expression. D) Enhancer: Enhancers are regulatory regions that can be located far from the gene they regulate and can increase the transcription of a gene. While enhancers are important for gene expression, the specific region that controls gene expression is the promoter. Therefore, the correct answer is C) Promoter, as it is the regulatory region in a gene that controls its expression by initiating transcription.