Plant Pathology MCQ Question and Answer | Agriculture MCQ Question

C₄ plants differ from C₃ plants in the number of ATPs consumed per hexose molecule.
C₄ carbon fixation is one of three known photosynthetic processes of carbon fixation in plants while the C₃ cycle is a series of biochemical redox reactions that take place in the stroma of chloroplast in photosynthetic organisms.
Both cycles require ATP for their process, but they differ in the number of ATP required. C₄ plants need 12 ATP's more than C₃ plants to synthesize per hexose molecule.

Nine-tenth of all photosynthesis in the world (85 - 90%) is carried out by algae of the ocean.
Algae are a diverse group of predominantly aquatic photosynthetic organisms, including cyanobacteria, green algae, and other eukaryotic algae. They account for 85 - 95% of the photosynthesis that takes place on Earth.
Algae have a wide range of antenna pigments to harvest light energy for photosynthesis giving different types of algae their characteristic colour.
Algae are indispensable because they produce about half the oxygen in Earth's atmosphere.

Leghemoglobin present in the root nodules of leguminous plants helps in nitrogen fixation by removing oxygen.
Leghemoglobin is an oxygen-carrying phytoglobin found in the nitrogen-fixing root nodules of leguminous plants.
It is produced by these plants in response to the roots being colonized by nitrogen-fixing bacteria, termed rhizobia, as part of the symbiotic interaction between plant and bacterium roots not colonized by Rhizobium do not synthesise leghemoglobin.
The main functions of leghemoglobin are to facilitate oxygen supply to the nitrogen-fixing bacteria and to protect the enzyme, nitrogenase from being inactivated by oxygen.

The selective media for Xanthomonas is yeast extract nutrient agar.
A selective medium (XMSM) was developed for isolation of Xanthomonas maltophilia from bulk soil and plant rhizosphere environments.
The XMSM basal medium contained maltose, tryptone, bromthymol blue and agar.

The law of limiting factors for photosynthesis was enunciated by Blackman.
In 1905 Frederick Blackman articulated the role of limiting factors as follows: "When a process is conditioned as to its rapidity by several separate factors the rate of the process is limited by the pace of the slowest factor."
The identification of a factor as limiting is possible only in distinction to one or more other factors that are non-limiting.

Yeast is a single cell fungus.
Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom.
Yeasts are unicellular organisms with some species having the ability to develop multicellular characteristics by forming strings of connected budding cells known as pseudo hyphae or false hyphae.
Yeast sizes vary greatly, depending on species and environment, typically measuring 3 - 4 µm in diameter, although some yeasts can grow to 40 µm in size.

Outer wall of pollen grain is formed of Sporopollenin.
Pollen grains have a hard coat made of sporopollenin that protects the gametophytes during the process of their movement from the stamens to the pistil of flowering plants, or from the male cone to the female cone of gymnosperms.
Each pollen grain contains vegetative cells and a generative (reproductive) cell. In flowering plants the vegetative tube cell produces the pollen tube, and the generative cell divides to form the two sperm nuclei.

Polar nuclei are located in the Embryo sac.
The female gametophyte is also commonly called the embryo sac or megagametophyte.
The female gametophyte develops within the ovule and generally consists of three antipodal cells, one central cell, two synergid cells, and one egg cell.
Central cell is formed by the fusion of two polar nuclei. Out of two, one is derived from the micropylar end and the other from the chalazal end.

Club root of crucifers can be controlled by the application of Lime.
Clubroot is a fungal disease that affects several plants in the cabbage family including cabbages, radishes, mustard and ornamentals such as candytuft. It is caused by the fungus Plasmodiophora brassicae and gets its name from the club-like roots it induces in infected plants.
Since problems are more severe in acid soils (pH 5.0 - 7.0) adding lime to acid soils can help control the disease.

The first product of photorespiration is Phosphoglycolate.
Photorespiration refers to a process in plant metabolism where the enzyme RuBisCO oxygenates RuBP, wasting some of the energy produced by photosynthesis.
Addition of molecular oxygen to ribulose-1,5-bisphosphate produces 3-phosphoglycerate (PGA) and 2-phosphoglycolate (2PG, or PG). PGA is the normal product of carboxylation and productively enters the Calvin cycle.
Phosphoglycolate, however, inhibits certain enzymes involved in photosynthetic carbon fixation.