Nokea
Which of the following is an example of a biological macromolecule?
- A. Monosaccharide
- B. Protein
- C. Nucleic acid
- D. Amino acid
Correct Answer: B
Rationale: The correct answer is B, 'Protein.' Proteins are biological macromolecules composed of amino acid chains. They play vital roles in cellular functions, including catalyzing reactions, providing structural support, and acting as signaling molecules. Monosaccharides are simple sugars, nucleic acids are genetic materials such as DNA and RNA, and amino acids are the fundamental units that make up proteins.
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After being absorbed in the small intestines, where do lipids first enter?
- A. Arteries
- B. Veins
- C. Intestinal spaces
- D. Lacteal vessels
Correct Answer: D
Rationale: After being absorbed in the small intestines, lipids first enter lacteal vessels. Lacteal vessels are part of the lymphatic system responsible for transporting dietary fats and fat-soluble vitamins. These vessels aid in the absorption and transport of lipids from the intestines to the bloodstream, playing a crucial role in the body's fat metabolism.
In a plant in which fuzzy leaves (F) are dominant over smooth leaves (f), which of the following crosses will reproduce only offspring with smooth leaves?
- A. FF by ff
- B. ff by ff
- C. Ff by Ff
- D. FF by FF
Correct Answer: B
Rationale: The correct answer is B: 'ff by ff.' When a plant with fuzzy leaves (Ff) is crossed with another plant with smooth leaves (ff), all the offspring will inherit one smooth leaf allele from the smooth-leaved parent, resulting in only smooth leaves. The genotype of the offspring will be ff, leading to the expression of smooth leaves. This cross ensures that both alleles for leaf texture are the recessive smooth allele (f), resulting in all offspring having smooth leaves.
Which of the following types of cells stimulates other immune cells to attack and destroy foreign agents?
- A. Cytotoxic T-cells
- B. Natural killer cells
- C. Helper T-cells
- D. Plasma cells
Correct Answer: C
Rationale: Helper T-cells play a crucial role in coordinating the immune response by activating and directing other immune cells, such as cytotoxic T-cells and macrophages, to attack and eliminate foreign invaders. They achieve this through the release of signaling molecules called cytokines, which regulate the immune system's response to infections and other challenges. Helper T-cells are also involved in activating B-cells to produce antibodies. Natural killer cells, on the other hand, are part of the innate immune system and can directly kill infected or abnormal cells without prior activation.
Which of the following nucleotides is only found in RNA?
- A. Adenine
- B. Uracil
- C. Guanine
- D. Thymine
Correct Answer: B
Rationale: The correct answer is B: Uracil. Uracil is a nucleotide base that is specifically found in RNA. In DNA, thymine replaces uracil. Adenine, guanine, and cytosine are nucleotides present in both RNA and DNA. Understanding the unique nucleotide composition of RNA and DNA is essential in molecular biology to comprehend the genetic information flow and transcription processes accurately. RNA uses uracil instead of thymine, which is a key distinction between the two nucleic acids.
Which of the following is classified as a noninfectious disease?
- A. Dengue
- B. Psoriasis
- C. Chikungunya
- D. Brucellosis
Correct Answer: B
Rationale: Psoriasis is classified as a noninfectious disease because it is linked to an overactive immune system that leads to skin inflammation and rapid skin cell growth. Unlike infectious diseases such as Dengue, Chikungunya, and Brucellosis, which are caused by bacteria, viruses, or other pathogens, Psoriasis does not spread through pathogens. Therefore, Psoriasis is the correct choice for a noninfectious disease.