Which of the following statements about genetics is correct?
A. Mendel’s law of segregation states that allele pairs separate during gamete formation.
B. Homozygous individuals have two different alleles for a trait.
C. A monohybrid cross gives a phenotypic ratio of 9:3:3:1.
D. Phenotype refers to the genetic makeup of an organism.
Answer: Option A
Solution (By JKSSB Mock Tests)
Mendel’s first law (segregation) states that the two alleles for a trait separate during gamete formation. Homozygous individuals have identical alleles; phenotype is observable trait; a monohybrid ratio is 3:1.
Explanation:
A synapse is a specialized junction where the axon terminal of one neuron communicates with the dendrite or cell body of another neuron via neurotransmitters. The axon hillock is where action potential initiates, nodes of Ranvier are gaps in myelin sheath, dendrites receive signals.
Explanation:
Diastole is the relaxation phase of the cardiac cycle, during which the ventricles fill with blood from the atria. Systole is the contraction phase, pumping blood out. Atrial contraction (atrial systole) contributes to ventricular filling. Ejection phase is part of ventricular systole when blood is ejected. Normal diastolic and systolic pressures are 80 and 120 mmHg respectively.
Explanation:
Commensalism (+/0) involves one species benefiting and the other neither harmed nor helped. Example: barnacles on a whale, or cattle egrets eating insects stirred by cattle. Mutualism benefits both (+/+), parasitism benefits one at expense of other (+/-), predation (+/-) involves killing. The distinction is based on the net effect.
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