Which of the following statements about DNA is correct?
A. It contains the sugar ribose.
B. It is located in the nucleus in eukaryotes.
C. Adenine pairs with guanine.
D. It is usually single-stranded.
Answer: Option B
Solution (By JKExamLibrary)
DNA is primarily located in the nucleus of eukaryotic cells. It contains deoxyribose (not ribose), is double-stranded, and adenine pairs with thymine. Thus, D is correct.
Explanation:
Electroporation uses an electric field to create temporary pores in the cell membrane, allowing DNA to enter. Heat shock is a chemical method using CaCl₂ and temperature shift, microinjection physically injects DNA into cells, biolistics is a gene gun for plant cells. Electroporation is efficient for many cell types.
Explanation:
Secretin, released from the duodenum in response to acidic chyme, stimulates the pancreas to secrete bicarbonate-rich fluid to neutralize the acid. Gastrin stimulates HCl, CCK enzyme secretion, motilin GI motility.
Explanation:
Meiosis I features crossing over (prophase I) and independent assortment of homologous chromosomes, creating genetic diversity in gametes. Mitosis produces identical cells, binary fission is asexual, fragmentation is a form of asexual reproduction.
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