Consider the following statements about the human excretory system: 1. ADH increases water reabsorption. 2. Aldosterone increases sodium reabsorption. 3. Renin converts angiotensinogen to angiotensin I. Which of the above is/are correct? MCQ with Answer and Explanation

Explanation:
Beriberi is caused by a severe deficiency of Vitamin B1 (Thiamine). It affects the cardiovascular system (wet beriberi, causing edema and heart failure) and the nervous system (dry beriberi, causing muscle wasting and nerve damage). It is common in populations whose staple diet is polished rice, as the thiamine-rich husk is removed during polishing.

Explanation:
Chiasmata become clearly visible during the diplotene stage of Prophase I. While the actual exchange of genetic material (crossing over) occurs during the pachytene stage, the homologous chromosomes begin to repel each other and move apart in diplotene, remaining connected only at the sites of crossing over, which appear as X-shaped chiasmata. Exam tip: Pachytene = crossing over; Diplotene = chiasmata visible.

Explanation:
Leucoplasts are colourless plastids that store nutrients: amyloplasts store starch, elaioplasts store lipids, aleuroplasts store proteins. Chloroplasts contain chlorophyll for photosynthesis, chromoplasts give yellow/orange colour (carotenoids), etioplasts are undeveloped chloroplasts in dark-grown plants. Amyloplasts are abundant in roots and tubers like potato.