Botany and Plant Science

The main difference between an animal cell and a plant cell is that plant cells have a cell wall, which the animal cells lack. The cell wall which is made up of cellulose gives the plant cell rigidity resulting in a fixed, rectangular shape. Animal cells lack the rigidity hence, they tend to have a round and irregular shape. Animal cells tend to vary greatly in appearance. The cell wall allows high pressure to build inside of the plant cell without bursting. Due to this, the plant cell is able to accept large amounts of liquid through osmosis without bursting. Animal cells, which only have a thin membrane restricting access to the cell, tend to burst if they absorb too much extra water.

Plant cell walls appear layered in cross-section because the cellulose microfibrils in different lamellae are oriented in varying directions during growth, causing optical differences in light refraction that highlight distinct layers.

In the maturation phase, the enlarged cells eventually acquire a specific size and form according to their location and role following biochemical, physiological and morphological changes, i.e., the cells undergo specialization or transformation. As a result, various kinds of cells get differentiated. These differentiated cells form different kinds of simple and complex tissues that perform different functions. This includes cell wall growth and protoplasm modification.

Spermatophytes are seed-bearing plants. Eucalyptus is an angiosperm (flowering plant) and Wolffia is an angiosperm; both produce seeds but do not produce cones, as cones are characteristic of gymnosperms like Pinus and Cycas.

An embryo is a portion of a seed that grows into a plant. An embryo is a basic element that possesses enough potential for further growth and development. The part of a plant embryo or seedling that lies between the radicle and the cotyledons is the hypocotyl. Upon germination, the hypocotyl pushes the cotyledons above the ground to develop. It eventually becomes part of the plant stem. Most seed-bearing plants have hypocotyls.

Algae are mostly haploid. They show haplontic lifestyle i.e. for the most part of the life haploid is the dominant stage. Fusion of gametes results in diploid sporophyte in algae which undergoes meiosis to form haploid gametophyte. There are no free-living sporophytes. The gametophyte is the dominant phase.

Sporophyte develops by diploid zygote and hence is diploid. Spores are produced on sporophyte by meiosis and hence are haploid. Haploid spores develop mitotically into the haploid multicellular gametophyte. Thus, spores and gametophyte exhibit haploid condition while sporophyte is diploid. 

In crop improvement programme, haploids are important because they form perfect homozygous lines. Homozygous are the pure line selection plants resulting from self pollination. In this way, considerable homozygosity is obtained. Haploids are those plants which possess a gametophytic number of chromosomes. Haploids are used in plant breeding, especially for the production of homozygous plants and in their studies in the detection of mutation.

Pollination is the transfer of pollen from an anther to a stigma, a process characteristic of seed-producing plants, which include both Gymnosperms and Angiosperms. Bryophytes and Pteridophytes rely on water for fertilization rather than pollination via pollen grains.

A scape is a leafless flowering stem that emerges directly from the ground or a bulb, common in plants like onions and lilies.

When a pollen grain from a stamen is transferred to the stigma of the same plant, it is called self-pollination. It mainly occurs in bisexual flowers.