Nokea
Which of the following nucleic acids carries the genetic information copied from DNA to the ribosomes?
- A. DNA
- B. mRNA
- C. rRNA
- D. tRNA
Correct Answer: B
Rationale: The correct answer is B: mRNA. Messenger RNA (mRNA) is responsible for carrying the genetic information copied from DNA to the ribosomes for protein synthesis. mRNA serves as a temporary copy of the genetic instructions stored in DNA and acts as a messenger between the nucleus and ribosomes in the cytoplasm where protein synthesis occurs. While rRNA (ribosomal RNA) and tRNA (transfer RNA) play essential roles in the process of translation at the ribosomes, mRNA is the nucleic acid directly involved in carrying the genetic code for protein synthesis. Therefore, choices A, C, and D are incorrect as DNA is the original genetic material, rRNA is a component of the ribosomes, and tRNA carries amino acids during protein synthesis, respectively.
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What is the main function of the skeletal system?
- A. To regulate blood pressure
- B. To protect internal organs
- C. To produce hormones
- D. To fight infection
Correct Answer: B
Rationale: The main function of the skeletal system is to provide structural support for the body, protect internal organs, facilitate movement, and produce blood cells in the bone marrow. Choice A, 'To regulate blood pressure,' is incorrect as blood pressure regulation is primarily controlled by the circulatory and endocrine systems. Choice C, 'To produce hormones,' is incorrect as hormone production is mainly carried out by the endocrine system. Choice D, 'To fight infection,' is incorrect as the immune system is responsible for fighting infections, not the skeletal system.
Which type of tissue provides support and structure to the body?
- A. Muscle tissue
- B. Connective tissue
- C. Nervous tissue
- D. Epithelial tissue
Correct Answer: B
Rationale: Connective tissue is the correct answer as it provides support, structure, and strength to the body by holding tissues and organs in place. Muscle tissue is primarily responsible for movement, nervous tissue for communication, and epithelial tissue for covering and lining surfaces. While muscle tissue allows for voluntary and involuntary movement, nervous tissue transmits electrical signals, and epithelial tissue acts as a protective barrier and is involved in absorption and secretion. Therefore, in the context of providing support and structure, connective tissue is the most appropriate choice.
What is a monohybrid cross, and what is the ratio of dominant to recessive gene manifestation?
- A. A cross involving two traits, 9:3:3:1
- B. A cross involving one trait, 3:1
- C. A cross involving two traits, 1:2:1
- D. A cross involving one trait, 1:1
Correct Answer: B
Rationale: A monohybrid cross is a genetic cross involving one trait. The ratio of dominant to recessive gene manifestation in the offspring is typically 3:1 when both parents are heterozygous. This ratio is the genotypic ratio, not just the phenotype ratio, where the dominant allele is present in 3 out of 4 offspring, and the recessive allele is present in 1 out of 4 offspring. Choice A is incorrect because it describes a dihybrid cross ratio. Choice C is incorrect as it represents the genotypic ratio for a monohybrid cross involving incomplete dominance. Choice D is incorrect as it does not reflect the typical ratio for a monohybrid cross.
Which valve prevents the backflow of blood into the left ventricle as it leaves through the aorta?
- A. Pulmonary semilunar valve
- B. Aortic semilunar valve
- C. Tricuspid valve
- D. Mitral valve
Correct Answer: B
Rationale: The aortic semilunar valve is the correct answer as it prevents the backflow of blood into the left ventricle once it has been pumped into the aorta. The pulmonary semilunar valve prevents backflow into the right ventricle, the tricuspid valve controls blood flow between the right atrium and ventricle, and the mitral valve regulates blood flow between the left atrium and ventricle. Therefore, option B is the correct choice for this question.
What are the components of the female internal genitalia and their functions?
- A. Fallopian tubes: transport eggs from the ovaries to the uterus
- B. Vagina: serves as the birth canal and connects the uterus to the external environment
- C. Ovaries: produce eggs and hormones
- D. Cervix: serves as the lower part of the uterus connecting it to the vagina
Correct Answer: C
Rationale: The correct answer is C. The ovaries are responsible for producing eggs (ova) and hormones (estrogen and progesterone). They are essential for reproduction, including the release of eggs for fertilization and for regulating the menstrual cycle. The fallopian tubes, as mentioned in choice A, transport eggs from the ovaries to the uterus for potential fertilization. The vagina, described in choice B, serves as the birth canal and also connects the uterus to the external environment. The cervix, as stated in choice D, is the lower part of the uterus that connects it to the vagina and also plays a role in protecting the uterus from infections and serving as a passage for menstrual flow.