Nokea
When human cells divide by meiosis, how many chromosomes do the resulting cells contain?
- A. 96
- B. 54
- C. 46
- D. 23
Correct Answer: D
Rationale: When human cells divide by meiosis, the resulting cells contain 23 chromosomes. This is because meiosis is a cell division process that reduces the chromosome number by half, resulting in cells with a haploid number of chromosomes. In humans, the diploid number of chromosomes is 46. Therefore, after meiosis, the resulting cells have 23 chromosomes, ensuring the correct chromosome number is restored upon fertilization. Choices A, B, and C are incorrect as they do not represent the correct chromosome number resulting from meiosis in human cells.
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What is the smallest unit that can encode for a trait?
- A. A codon
- B. A gene
- C. A nucleotide
- D. A chromosome
Correct Answer: B
Rationale: The correct answer is B - a gene. Genes are the smallest units that can encode for a trait as they contain the specific instructions for producing a particular characteristic or protein. While codons are sequences of nucleotides that code for specific amino acids in a protein, they are not the smallest unit that encodes for a trait. Nucleotides are the building blocks of DNA and RNA, and chromosomes are made up of DNA and proteins, containing many genes.
What type of bond connects sugar and phosphate in DNA?
- A. Hydrogen
- B. Ionic
- C. Covalent
- D. Overt
Correct Answer: C
Rationale: The correct answer is Covalent (C). In DNA, a covalent bond connects sugar and phosphate molecules. This bond involves the sharing of electron pairs between the atoms, providing stability to the DNA structure. Hydrogen bonds are important in DNA structure but are not the primary bond connecting sugar and phosphate. Ionic bonds involve the transfer of electrons, and 'overt' is not a term related to the bond connecting sugar and phosphate in DNA.
Which type of cell secretes antibodies?
- A. Bacterial cells
- B. Viral cells
- C. Lymph cells
- D. Plasma cells
Correct Answer: D
Rationale: The correct answer is D: Plasma cells. Plasma cells are a type of white blood cell that secretes antibodies. Antibodies are essential components of the immune system, as they help in identifying and neutralizing pathogens. Choice A, B, and C are incorrect as bacterial cells and viral cells do not secrete antibodies, and lymph cells are involved in the immune response but do not secrete antibodies like plasma cells.
What is the pathway of oxygenated blood from the lungs?
- A. Lungs to the left atrium, through the mitral valve into the left ventricle, pumped into the aorta upon contraction, then dispersed to tissues via a network of arteries and capillaries
- B. Lungs to the right atrium, through the mitral valve into the right ventricle, pumped into the aorta upon contraction, then dispersed to tissues via a network of arteries and veins
- C. Lungs to the left atrium, directly to the right aorta, then dispersed to tissues via a network of arteries and capillaries
- D. Lungs to the left atrium, through the septal valve, stored in the left ventricles, then dispersed to tissues via a network of arteries and capillaries
Correct Answer: A
Rationale: The correct pathway of oxygenated blood from the lungs is as follows: Oxygenated blood travels from the lungs to the left atrium, then passes through the mitral valve into the left ventricle. From there, it is pumped into the aorta upon contraction of the heart and is then dispersed to various tissues throughout the body via a network of arteries and capillaries. Choice B is incorrect as it incorrectly mentions the right atrium and ventricle, which are associated with deoxygenated blood. Choice C is incorrect as it mentions a direct connection to the right aorta, which does not exist in the circulatory system. Choice D is incorrect as it refers to the septal valve (which is not anatomically correct) and storing blood in the left ventricle, which does not occur in the normal circulation of blood.
Where does the majority of nutrient absorption occur?
- A. Mouth
- B. Stomach
- C. Small intestine
- D. Large intestine
Correct Answer: C
Rationale: The majority of nutrient absorption occurs in the small intestine. The small intestine is where the final stages of digestion take place, and it is specialized for absorption with its large surface area and villi that increase nutrient absorption efficiency. The mouth is responsible for mechanical digestion through chewing, the stomach primarily aids in digestion through mixing and breakdown of food, and the large intestine mainly absorbs water and electrolytes, with minimal nutrient absorption.