The branch of biology concerned with the study of insects is: MCQ with Answer and Explanation

Explanation:
Pellagra, characterized by dermatitis, diarrhea, and dementia (3 Ds), is caused by a deficiency of niacin (vitamin B₃) or its precursor tryptophan. It is common in populations with corn-based diets lacking tryptophan. Beriberi is due to B₁ deficiency, cheilosis to B₂, peripheral neuropathy to B₆. Niacin is a component of coenzymes NAD and NADP.

Explanation:
The left ventricle has the thickest muscular wall to pump blood at high pressure into the systemic circulation. The sinoatrial (SA) node generates impulses spontaneously, acting as the natural pacemaker. The tricuspid valve is located between the right atrium and right ventricle; the bicuspid (mitral) valve is on the left side. Thus, statements 1 and 3 are correct.

Explanation:
Gregor Mendel, through his pea plant experiments, established the fundamental laws of inheritance, earning him the title 'father of genetics'. Edward Jenner pioneered the concept of vaccination by developing the first successful smallpox vaccine using cowpox material. Charles Darwin proposed the theory of evolution by natural selection, not the cell theory (proposed by Schleiden and Schwann). Thus, statements 1 and 2 are correct.