Biology (CDS-Solved Paper)

Food chain is the linear sequence of transfer of matter and energy in the form of food from organism to organism. It begins from the producer organisms, i.e. plants, and ends with decomposer species like bacteria, fungi, etc.

Active transport is the movement of molecules across a membrane, from a region of their lower concentration to a region of their higher concentration, i.e. aganist the diffusion or concentration gradient. Active transport always requires cellular energy to achieve this movement.

Chlorophyll in photosynthetic prokaryotic bacteria is associated with membranous vesicles. These organisms lack membrane bound organelles (such as chloroplast). They have infoldings of the plasma membrane present in the scattered form in cytoplasm for attachment of chlorophyll. These carryout photosynthesis.

Trypanosoma is responsible for sleeping-sickness. It is a vector borne disease, transmitted to humans by the tse-tse fly. Its symptoms include, fever, headache, joint pains and poor mental and physical coordination.

Amongst the options that are given, ‘biceps’ does not have smooth muscles. Smooth muscles are involuntary muscles as their functioning cannot be directly controlled by our own will.
The muscle present in the biceps as well as triceps are called skeletal or striated or voluntary muscles. We can control the movements of these muscles.

Lysosomes are the cell organelles which are known as ‘suicidal bags’ of a cell. They contain powerful hydrolytic enzymes which are capable of breaking down all organic material present inside the cell.
During the disturbance in cellular metabolism or when the cell gets damaged, lysosomes may burst and the enzymes digest their own cell. Therefore, they are also known as suicidal bags of a cell.

The successional development of vegetation community in a habit at depends on many factors. In the begining an area is bare, with time there begins migration of people to that area. This is followed by reaction of people to changing environment condition and lastly people try to stabilise in a given area with certain set of climatic condition. Therefore, the correct sequence is nudation, migration, reaction and stabilisation.

Vitamin-C is known as ascorbic acid. It is found in all citrus fruits. It’s deficiency in diet comes scurvy.

Animal cell does not possess cell wall. It is present in the plant cells, outside the plasma membrane as a rigid outer covering. It maintains the shape of the cell and protects it. Cell wall is also present in fungi, algae and bacteria.

Marsilea, fern and horse-tail are examples of division–Pteridophyta of plant kingdom. In this group, the plant body is differentiated into roots, stem and leaves and has specialised tissue for the conduction of water and other substances from one part of the plant body to another.