Nokea
Which of the following statements best describes the function of a buffer?
- A. It permanently binds hydrogen ions.
- B. It causes the pH of a solution to become neutral.
- C. It decreases the pH of the solution.
- D. It enables resistance to a change in pH.
Correct Answer: D
Rationale: The correct answer is D: 'It enables resistance to a change in pH.' Buffers function by resisting changes in pH when small amounts of acid or base are added to a solution, thereby maintaining a stable pH. Option A is incorrect because buffers do not permanently bind hydrogen ions; they can release or absorb them as needed to maintain pH. Option B is incorrect because buffers do not necessarily cause a solution's pH to become neutral; they stabilize the pH at a specific value. Option C is incorrect; buffers can increase or decrease pH depending on the conditions to maintain stability. Therefore, the best description of a buffer's function is its ability to resist changes in pH.
You may also like to solve these questions
After infecting host cells, how does the AIDS virus, which contains RNA, insert viral DNA into the host T-cell?
- A. Receptor proteins located on the surface of the virus
- B. Reverse transcriptase, an enzyme encoded by the virus
- C. The phospholipids found on the envelope of the virus
- D. The protein that makes up the capsid of the virus
Correct Answer: B
Rationale: Reverse transcriptase is an essential enzyme unique to retroviruses like the AIDS virus. It catalyzes the conversion of viral RNA into DNA through a process known as reverse transcription. The newly formed viral DNA is then integrated into the host cell's genome, enabling the virus to replicate and establish a persistent infection within the host.
What primarily makes up the 'gray matter' of the brain?
- A. Meninges
- B. Neuron cell bodies
- C. Corpus callosum
- D. Neuron cell axons
Correct Answer: B
Rationale: The 'gray matter' of the brain primarily consists of neuron cell bodies. Gray matter is responsible for processing information in the brain as it contains the cell bodies of neurons, dendrites, and unmyelinated axons. Meninges are the protective membranes covering the brain and spinal cord, the corpus callosum is a structure connecting the two brain hemispheres, and neuron cell axons are part of the white matter in the brain.
In pea plants, green pod color (G)is dominant to yellow pod color (g). A cross was done between a plant with green pods and plant with yellow pods. Of the resulting offspring. 50% had green pods and 50% had yellow pods. Which of the following we the genotypes of both present plants?
- A. GG X GG
- B. Gg × gg
- C. Gg × gg
- D. Gg × Gg
Correct Answer: D
Rationale: The 50% green and 50% yellow offspring suggests that one parent was heterozygous (Gg) and the other was homozygous recessive (gg), leading to a 1:1 ratio of green to yellow.
Which laboratory method is most useful to separate genomic DNA fragments by size?
- A. Titration
- B. Spectrophotometry
- C. Electrophoresis
- D. Filtration
Correct Answer: C
Rationale: Electrophoresis is the most suitable laboratory method for separating genomic DNA fragments by size. It works by subjecting DNA fragments to an electric field, causing them to migrate through a gel matrix based on size differences. Smaller fragments move faster and travel farther than larger ones, allowing for separation and analysis based on size. Titration is a technique used to determine the concentration of a solution, not to separate DNA fragments by size. Spectrophotometry is used to measure the amount of light absorbed by a substance at different wavelengths, not for DNA fragment size separation. Filtration is a method used to separate solid particles from a liquid or gas by passing it through a filter medium, not for separating DNA fragments by size.
Which of the following cells secrete bone material?
- A. Chondrocyte
- B. Odontocyte
- C. Ameloblast
- D. Osteocyte
Correct Answer: D
Rationale: Osteocytes are the cells responsible for maintaining bone tissue and secreting bone material, contributing to the overall structure and strength of bones.