(a) This cottony mass is of bread mould, belong to the group fungi. The spores of the mould present in air, settle down on the moist bread piece (and also on other moist dead organic matter). Spores grow into small or big colonies (patch) consisting of thread like structure called hyphae. Eating of such spoiled bread causes diseases.
(b) Fungi (mould) do not have chlorophyl. They obtain their food from dead decaying organic matter, such as bread or other food materials, so they are called saprophytes.
(c) Fungi decompose complex dead organic materials into usable simpler forms. Thus, they help in recycling of materials. Also help in cleaning of the environment.

The criteria for classification of plant kingdom into divisions depend upon:
(a) differentiation of plant body components,
(b) presence of transport (conduction) tissues,
(c) ability to produce seeds, and
(d) enclosure of seeds in fruits.
On these basis animals cannot be classified because animals do not exhibit these characteristics. Animals on the other hand are classified on the basis of presence or absence of coeloem, symmetry, features of embryonic development and organisation of cells to form tissues and organ, etc.

Major divisions in kingdom plantae are-
(i) Thallophyta
(ii) Bryophyta
(iii) Pteridophyta
(iv) Gymnosperms
(v) Angiosperms.
Basis for classification plantae division:
1. Whether the plant body has well differentiated, distinct components.
2. Whether the plant body has special tissues for the transport of water and other substances within it.
3. Whether the plants bear the seeds or not.
4. Whether the seeds are enclosed within fruits or not.

The basis for grouping organisms into five kingdoms are:
(i) Whether the organisms are made of prokaryotic or eukaryotic cells.
(ii) Whether the organism is unicellular i.e., a cell living singly or organised into multicellular and thus complex organisms.
(iii) Whether the cells have a cell wall or not.
(iv) Whether they prepare their own food or get their food from outside.

We classify organisms due to the following reasons:
(i) Classification makes the study of huge varieties of organisms easy.
(ii) It reveals before us a picture of all forms of organisms at a glance.
(iii) It helps us to understand the interrelationship among different groups of organisms.
(iv) It serves as a base for the development of other pure biological science e.g., biogeography i.e., geographical distribution of plants and animals.
(v) It also helps in understanding and development of other applied branches of science such as agriculture, public health and environmental biology.

(i) Angiosperm
(a) Presence of flowers, seeds and fruits.
(b) Presence of root, stem and leaves.
(c) Presence of xylem vessels and phloem sieve tubes.
(ii) Moss
(a) Absence of roots.
(b) Presence of rhizoids.
(c) Leaves one cell thick.
(iii) Alga
(a) Green in colour.
(b) Plant body is thalloid.

Difference between Bryophyta and Pteridophyta:

In spite of certain external differences, plants and animals show a number of very obvious similarities which are as follows:
(i) Plants and animals are made up of microscopic units-the cell.
(ii) Both contain living substance protoplasm.
(iii) Certain life processes i.e., respiration, digestion, reproduction, assimilation etc. take place in both the groups in identical manner.
 (iv) Both show response to external stimuli.
(v) They both show growth.
(vi) Both reproduce and pass on their hereditary characters to the offspring by the same mechanism.

(i) Kingdom. Highest category of classification.
(ii) Phylum (for animals) Division (for plants). A group of closely related classes having certain common characters.
(iii) Class. A group of closely related orders having certain common characters.
(iv) Order A group of closely related families having certain on characters.
(v) Family. A group of closely related genus having certain on characters.
(vi) Genus. A group of closely related species have certain common characters.
(vii) Species.  A group of organisms which are similar enough to breed and perpetuate.