Optionals IAS Mains Botany: Questions 1 - 10 of 511

TS Leaf of Cordaites

Cordaites are primitive trees that went extinct millions of years ago. In transverse section of leaf showing various part like xylem, phloem epidermis and bundle sheath.

Kranz Anatomy

• Kranz anatomy is a special structure in the leaves of plants that have a C₄ pathway of carbon dioxide fixation.
• The leaves contain a ring of mesophyll cells, containing a few small chloroplasts concerned with the initial fixing of carbon dioxide, surrounding a sheath of parenchyma cells (the bundle sheath) which has large chloroplasts i…

Meaning of VAM

• VAM means Vesicular Arbuscular Mycorrhizal.
• Mycorrhiza is the product of an association between a fungus and plant root.
• Vesicular arbuscular mycorrhiza (VAM) is a fungus and formed by the symbiotic association between certain phycomycetous fungi and angiosperm roots.
• They help them to capture nutrients from the soil.
• These fungi are scie…

Gnetum is Dioecious

• The reproductive organs are organized into well-developed cones or strobili.
• Gnetum have male and female reproductive organs on separate plants.
• Gnetum belongs to gymnosperms so they do not have flowers and instead of that cones or strobili sporangia bearing structure present at the tip of the axis.

Male Cone or Staminate Strobilus

• T…

Polyembryony

• Polyembryony is the process in which the fertilization of single egg leads to the formation of two or more embryos.
• Polyembryony is common in mango and citrus.

Importance

• It is importance in the formation of identical twins.
• Formation of embryos by cells of the embryo sac other than the egg and embryo develop from additional embryo sacs in …

Salient Features of Family Poaceae

• Small reduced flowers on tufted or caespitose plants with linear sheathing leaves.
• Differing from the Cyperaceae with its round stems, hollow at the inter-nodes and leaves 2-ranked or arranged in 2 rows.
• Sheathing leaf bases are also often open or loosely connected to the culm and often showing a ligule at the point …

Raising Haploids from Microspores

• Haploid plants possess only a single set of chromosomes in the sporophyte.
• Haploid plants are significance for the production of homozygous plants and for the improvement of plants in plant breeding programmers.

Production of Haploid Plants

Haploids may be divided in two categori…

Palmella Stage

• Palmella stage is a type of asexual reproduction and is found in some algae manly in Euglena and Chlamydomonas.
• Palmella stage is formed in unfavourable conditions.
• Under unfavourable conditions, zoo-spores are remain enclosed with the parent cell wall and is grows in size and divided and large numbers of zoo-spores are found without fl…

Allium Type of Embryo Sac

• Allium is a bisporic type of embryo sac.
• When two megaspore nuclei participate in the development of embryo sac it is known as bisporic type of embryo sac.
• Bisporic development occurs when either chalazal or micropylar dyad undergoes the second meiotic division.
• In Allium type, non-functional dyad degenerates and functional dy…

Tundu Disease of Wheat

• Tundu disease of wheat is also called as yellow Ear rot or Ear cockle.
• Tundu is a minor disease problem worldwide.
• It is quite common in north-west regions of India.
• This disease of wheat was first reported by Hutchinson in 1917 from Punjab.
• Now it is spread in many other parts of the country like Haryana, U. P. , Rajasthan, M. P.…