Nokea
What are the microscopic units responsible for muscle contraction called?
- A. Neurons
- B. Myofibrils
- C. Tendons
- D. Sarcomeres
Correct Answer: D
Rationale: Sarcomeres are the fundamental contractile units of skeletal muscles and are responsible for muscle contraction. They consist of actin and myosin filaments that slide past each other during muscle contraction. Neurons are responsible for transmitting signals to and from muscles but are not directly involved in muscle contraction. Myofibrils are composed of sarcomeres and are the structures within muscle cells where muscle contractions take place. Tendons are connective tissues that attach muscles to bones and are not directly involved in muscle contraction.
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Histamine, released during an allergic reaction, causes symptoms like:
- A. Fever and fatigue
- B. Runny nose and itchiness
- C. Muscle aches and joint pain
- D. Cough and shortness of breath
Correct Answer: B
Rationale: Histamine is a chemical released by the immune system during an allergic reaction. It is responsible for causing symptoms such as a runny nose, itchiness, sneezing, and watery eyes. These symptoms are commonly seen in allergies like hay fever. Fever and fatigue (option A) are not typically caused by histamine release during an allergic reaction. Muscle aches and joint pain (option C) are not common symptoms of histamine release in allergic reactions. Cough and shortness of breath (option D) are more commonly associated with asthma or respiratory allergies rather than histamine release.
What is the scientific name for the kneecap?
- A. Patella
- B. Femur
- C. Tibia
- D. Fibula
Correct Answer: A
Rationale: The correct answer is A: Patella. The patella is the scientific term for the kneecap, a small, flat, triangular bone situated in front of the knee joint. The femur, tibia, and fibula are also bones in the leg, but they are not synonymous with the kneecap. The femur is the thigh bone, the tibia is the shin bone, and the fibula is the outer lower leg bone. Therefore, the correct term for the kneecap specifically is the patella.
Differentiate between genotype and phenotype in the context of gene expression.
- A. Genotype refers to the physical manifestation of a trait, while phenotype represents its underlying genetic makeup.
- B. Genotype encompasses the spectrum of possible traits encoded by an organism's genes, while phenotype signifies the specific trait observed.
- C. Genotype denotes the presence of dominant alleles, while phenotype reflects the influence of recessive alleles.
- D. There is no distinction; both terms are interchangeable.
Correct Answer: B
Rationale: - Genotype refers to the genetic makeup of an organism, including all the genes and alleles it possesses.
- Phenotype, on the other hand, refers to the observable physical characteristics or traits of an organism, which result from the interaction between its genotype and the environment.
- While genotype represents the genetic potential or range of traits that an organism can express, phenotype reflects the actual expression of specific traits.
- Therefore, option B correctly captures the distinction between genotype and phenotype in the context of gene expression.
What is the structure surrounding and protecting the testes, maintaining the optimal temperature for sperm production?
- A. Epididymis
- B. Vas deferens
- C. Scrotum
- D. Prostate gland
Correct Answer: C
Rationale: The scrotum is the structure that surrounds and protects the testes. It plays a vital role in maintaining an optimal temperature for sperm production by adjusting the distance of the testes from the body to regulate the effects of external temperature changes. This mechanism helps to safeguard the viability and quality of sperm by ensuring they develop at the right temperature. The epididymis (Choice A) is a coiled tube where sperm mature and are stored, not the structure surrounding the testes. The vas deferens (Choice B) is a duct that carries sperm from the testes to the urethra, not the protective structure around the testes. The prostate gland (Choice D) is part of the male reproductive system, responsible for secreting fluids that nourish and protect sperm, but it is not the structure that surrounds and protects the testes for sperm production.
How does the structure of centromeres contribute to chromosome movement during mitosis?
- A. The centromere provides a binding site for spindle fibers, allowing chromosomes to be attached and manipulated.
- B. The centromere serves as a dividing point between sister chromatids, ensuring their separation during anaphase.
- C. The centromere maintains chromosome stability by preventing chromosomal breaks and rearrangements.
- D. The centromere plays a role in DNA replication, ensuring accurate copying of the genetic material.
Correct Answer: A
Rationale: A) The centromere provides a binding site for spindle fibers, which are microtubules that help move chromosomes during cell division. This attachment allows the chromosomes to be pulled towards opposite poles of the cell during mitosis. Therefore, the structure of centromeres directly contributes to chromosome movement during mitosis by facilitating the attachment and manipulation of chromosomes by the spindle fibers.
B) While the centromere does serve as a dividing point between sister chromatids, ensuring their separation during anaphase, this function is more related to the segregation of chromosomes rather than their movement.
C) The centromere does play a role in maintaining chromosome stability by ensuring proper chromosome segregation, but it is not primarily responsible for preventing chromosomal breaks and rearrangements.
D) The centromere is not directly involved in DNA replication. Its main function is