Consider statements about scientists: 1. Robert Hooke discovered cells. 2. Antonie van Leeuwenhoek discovered bacteria. 3. Charles Darwin proposed the cell theory. Which are correct? MCQ with Answer and Explanation
Consider statements about scientists: 1. Robert Hooke discovered cells. 2. Antonie van Leeuwenhoek discovered bacteria. 3. Charles Darwin proposed the cell theory. Which are correct?
A. 1 and 3 only
B. 2 and 3 only
C. 1, 2 and 3
D. 1 and 2 only
Answer: Option D
Solution (By JKSSB Mock Tests)
Robert Hooke, in 1665, observed dead cork tissue under a microscope and coined the term 'cell' for the box-like structures he saw. Antonie van Leeuwenhoek, using his superior single-lens microscopes in the 1670s, was the first to observe and describe living microorganisms, including bacteria and protozoa. Charles Darwin proposed the theory of evolution by natural selection; the cell theory was proposed by Matthias Schleiden and Theodor Schwann. Thus, statements 1 and 2 are correct.
Explanation:
Diabetes insipidus results from insufficient ADH or kidney response, causing polyuria and polydipsia with dilute urine. Diabetes mellitus is hyperglycemia.
Explanation:
Phloem is the vascular tissue responsible for translocation of photosynthates (mainly sucrose) from source (leaves) to sink (roots, fruits, growing regions) via sieve tubes and companion cells. Xylem transports water and minerals upward. Collenchyma and sclerenchyma are mechanical tissues. Phloem is alive at maturity.
Explanation:
Alexander Fleming, a Scottish bacteriologist, discovered penicillin in 1928. He returned from a vacation to find that a Petri dish containing Staphylococcus bacteria had been accidentally contaminated by a mold. He noticed a clear zone around the mold where the bacteria had been killed. The mold was identified as Penicillium notatum, and the antibacterial substance was named penicillin.
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