Biology Test 265

Watson and Crick described double helical model for secondary structure of B-form of DNA which is physiologically most important form of DNA. Later on several other forms of DNA were discovered like A form and Z form.

Scotoactive stomata are the stomata that open in the dark and remain open during the night in absence of the sunlight. These stomata are found in plants like Bryophyllum. These stomata perform their activity during the night and close during the day in presence of the sunlight.

The members of rhodophyceae are commonly called red algae because of the predominance of the red pigment, r-phycoerythrin in their body.

The build-up of the chemical DDT in zooplanktons is a good example of biomagnification. These zooplanktons are eaten by little fish. Small fish are eaten by large fish, which are then eaten by a fish-eating bird at the tropic level's highest point. As a result, the organism at the highest trophic level (tertiary or quaternary) accumulates the most hazardous chemicals.

Mitochondria (sing.: mitochondrion), unless specifically stained, are not easily visible under the microscope. The number of mitochondria per cell is variable depending on the physiological activity of the cells.

A person with blood group A can receive blood from persons with blood groups A and O as persons with ‘A’ blood group has A antigen and anti-b antibody. A person with blood group O has no antigens.

Saheli is a steroidal formulated by CDRI lucknow.

Migration is going from one place to another.

The squamous epithelium is made of a single thin layer of flattened cells with irregular boundaries. They are found in the walls of blood vessels and air sacs of lungs and are involved in functions like forming a diffusion boundary.

Propionibacterium is a Gram-positive, non-motile bacterium that plays an important role in the creation of Emmental cheese, and to some extent, Jarlsberg cheese, Leerdammer and Maasdam cheese. Its concentration in Swiss-type cheeses is higher than in any other cheese.