Principles of Inheritance and Variation — BIOLOGY STD 12 Science — Question

What are Eurythermic species?

How do neutrophils act as a cellular barrier to pathogens in humans?

Match Column I with Column II.

S. No.	Column I	S. No.	Column II
A.	Acrosome	1.	Motility of sperm towards the egg.
B.	Head	2.	Powerhouse of the sperm; contains a number of mitochondria.
C.	Tail	3.	Contains the genetic material.
D.	Middle piece	4.	Contains enzymes to dissolve egg envelopes.

Why EtBr is used in gel electrophoresis inspite of it being highly carcinogenic?

Given below is a section of maize grain. Identify A and state its function.

What is called such a sequence of base pairs, which is read same in both the strands of DNA if the reading orientation is kept the same?

What is the purpose of using Mg²⁺ during annealing process of PCR?

Directions: In the following questions, the Assertions (A) and Reason(s) (R) have been put forward. Read both the statements carefully and choose the correct alternative from the following:
Assertion: PCR can detect very low amounts of DNA and is now routinely used to defect HIV in suspected AIDS patient.
Reason: PCR is a powerful technique to identify many other genetic disorders.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
3. Assertion is correct but Reason is incorrect.
4. Both Assertion and Reason are incorrect.

A Volcano erupted in Hawaii, and lava covered land that had been framed for centuries. Eventually, new lichens, and then plants, grew on the lava. Is this an example of primary or secondary successions? Give the reason also.

Identify True/ False statements. Correct each false statement to make it true.
Leydig cells are found in ovary. (True/ False)