The term for a sequence of three nucleotides on mRNA that specifies an amino acid is:
A. Anticodon
B. Intron
C. Exon
D. Codon
Answer: Option D
Solution (By JKExamLibrary)
A codon is a triplet of nucleotides in mRNA that codes for a specific amino acid or signals termination of translation. There are 64 codons; 61 code for amino acids and 3 are stop codons. Anticodons are on tRNA, exons are coding regions of DNA, introns are non-coding.
Explanation:
Abscisic acid (ABA) is a stress hormone that induces stomatal closure by causing efflux of K⁺ ions from guard cells, leading to loss of turgor, thereby reducing water loss during drought. Auxin and cytokinin promote growth, gibberellin stimulates stem elongation and seed germination. ABA also promotes seed dormancy and leaf senescence.
Explanation:
The SA node, located in the right atrium, spontaneously generates electrical impulses, setting the heart rate. It is the natural pacemaker. The AV node delays the impulse before it reaches the ventricles.
Explanation:
The common garden pea is scientifically named Pisum sativum. It belongs to the family Fabaceae. Mendel chose this plant for his genetic experiments because it has easily distinguishable contrasting traits, a short generation time, and is primarily self-pollinating. Cicer arietinum is chickpea, and Phaseolus vulgaris is the common bean.
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