Nokea
The muscular diaphragm plays a vital role in respiration. When it contracts, it:
- A. Increases lung volume for inhalation
- B. Decreases lung volume for exhalation
- C. Filters dust and particles from inhaled air
- D. Produces mucus to lubricate the airways
Correct Answer: A
Rationale: The muscular diaphragm plays a crucial role in respiration by contracting and flattening during inhalation. This action increases the volume of the thoracic cavity, which leads to a decrease in pressure within the lungs, allowing air to rush in and fill the expanded space. Choice B is incorrect because the diaphragm contracting increases the lung volume for inhalation, not decreases it for exhalation. Choice C is incorrect as the role of filtering dust and particles is primarily performed by the respiratory system's other structures like the nasal passages and the mucous membranes. Choice D is incorrect as mucus production is mainly carried out by specialized cells in the respiratory system and not by the diaphragm.
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The dark, round structures observed within some bacterial cells are most likely:
- A. Ribosomes
- B. Flagella
- C. Endospores
- D. Capsules
Correct Answer: C
Rationale: Endospores are the correct answer. Endospores are dark, round structures observed within some bacterial cells. They are highly resistant dormant structures formed by certain bacteria in response to harsh environmental conditions. Ribosomes are not dark, round structures within bacterial cells; they are responsible for protein synthesis. Flagella are long, whip-like appendages used for movement and are not dark, round structures within bacterial cells. Capsules are outer layers of polysaccharides that some bacteria produce for protection and adherence, not dark, round structures within bacterial cells.
Testosterone is a crucial hormone in the male reproductive system. What is its primary function?
- A. Egg production
- B. Sperm production and development
- C. Regulation of the menstrual cycle
- D. Milk production
Correct Answer: B
Rationale: Testosterone is a hormone primarily produced in the testes of males and is responsible for the development of male reproductive tissues, including the testes and prostate. Its primary function is the production and maturation of sperm cells, as well as the development of secondary sexual characteristics in males. Choice A, 'Egg production,' is incorrect as testosterone is not involved in the production of eggs. Choice C, 'Regulation of the menstrual cycle,' is incorrect because testosterone is not responsible for regulating the menstrual cycle, which is primarily governed by female hormones. Choice D, 'Milk production,' is incorrect as testosterone does not play a role in milk production, which is associated with other hormones like prolactin in females.
What is the structural and functional unit of the kidney responsible for filtering blood?
- A. Nephron
- B. Ureter
- C. Urethra
- D. Bladder
Correct Answer: A
Rationale: The nephron is the correct answer. It is the structural and functional unit of the kidney responsible for filtering blood. The nephron consists of a renal corpuscle (glomerulus and Bowman's capsule) and a renal tubule. Within the nephron, blood is filtered to form urine, which is then carried to the ureter for excretion from the body. Choices B, C, and D are incorrect because the ureter, urethra, and bladder are not involved in the filtration of blood in the kidney. Instead, they are parts of the urinary system responsible for transporting and storing urine.
What is the term for an organism with two different alleles for a gene?
- A. Homozygous
- B. Heterozygous
- C. Dominant
- D. Recessive
Correct Answer: B
Rationale: Homozygous refers to an organism with two identical alleles for a gene, either both dominant or both recessive. Heterozygous, the correct answer, refers to an organism with two different alleles for a gene, one dominant and one recessive. Dominant and recessive describe the relationship between alleles, where dominant alleles are expressed over recessive alleles in heterozygous individuals. Therefore, the term for an organism with two different alleles for a gene is 'heterozygous.'
The immune response can be categorized into two main branches:
- A. Humoral and cellular
- B. Innate and adaptive
- C. Primary and secondary
- D. Active and passive
Correct Answer: A
Rationale: - The immune response can be broadly categorized into two main branches: the humoral immune response and the cellular immune response.
- The humoral immune response involves the production of antibodies by B cells and is primarily responsible for defending against extracellular pathogens such as bacteria and viruses in the bloodstream and tissues.
- The cellular immune response involves the activation of T cells, which can directly kill infected cells or help coordinate the immune response. This branch is crucial for combating intracellular pathogens like viruses and some bacteria.
- Options B, C, and D do not accurately represent the main branches of the immune response and are therefore incorrect.