Plant Pathology MCQ Question and Answer | Agriculture MCQ Question

Blackman's law was conceived in connection with Photosynthesis.
The Blackman reaction is the name given to the rate-determining process. when photosynthesis is saturated with both light and carbon dioxide.
Blackman theorized that at moderate light intensities, the "light" reaction limits or "paces" the entire process. In other words, at these intensities, the dark reaction is capable of handling all the intermediate substances produced by the light reaction.

The male gametophyte of angiosperms/monocots is Microspore.
Microspores are land plant spores that develop into male gametophytes, whereas megaspores develop into female gametophytes.
The male gametophyte gives rise to sperm cells, which are used for fertilization of an egg cell to form a zygote. Microspores are haploid and are produced from diploid microsporocytes by meiosis.
As the anther of a flowering plant (angiosperms) develops, four patches of tissue differentiate from the main mass of cells. These patches of tissue contain many diploid microsporocyte cells, each of which undergoes meiosis producing a quartet of microspores.

In angiosperms, a mature male gametophyte is formed from a pollen mother cell through one meiotic and two mitotic divisions.
Microsporogenesis in the anther involves the meiotic division of pollen mother cells, which each produce four microspores.
Mature pollen development consists of meiotic and mitotic divisions after meiotic division microspores are generated by microsporocytes and each microspore undergoes asymmetric mitotic division, referred to as pollen mitosis I (PMI), forming the vegetative cell and the generative cell.

Root pressure is maximum when Transpiration is low and absorption high.
The transpiration process in plants creates a suction pressure that pulls up water from the xylem of the roots to the stem and then to the leaves.
Root pressure is the transverse osmotic pressure within the cells of a root system that causes sap to rise through a plant stem to the leaves.
When root pressure is maximum, the rate of absorption is higher whereas the loss of water through transpiration is less.

The first reduction in the pentose phosphate pathway is the Oxidation of glucose 6-phosphate.
The pentose phosphate pathway (PPP) branches from glucose 6-phosphate (G6P), produces NADPH and ribose 5-phosphate and shunts carbons back to the glycolytic or gluconeogenic pathway.
The first enzyme in this pathway is glucose-6-phosphate dehydrogenase (G6PDH) which produces NADPH, a substrate utilized for lipogenesis and glutathione regeneration by glutathione reductase.
The PPP has been demonstrated to be a major regulator for cellular reduction-oxidation (redox) homeostasis and biosynthesis.

Photophosphorylation is the process in which CO₂ and O₂ unite.
Photophosphorylation is the conversion of ADP to ATP using the energy of sunlight by activation of PSII. This involves the splitting of the water molecule into oxygen and hydrogen protons (H⁺), a process known as photolysis.
The concentration of NADPH in the chloroplast may help regulate which pathway electrons take through the light reactions. When the chloroplast runs low on ATP for the Calvin cycle, NADPH will accumulate and the plant may shift from noncyclic to cyclic electron flow.

Race-specific resistance is called Vertical resistance.
Race-specific or vertical resistance implies resistance to some pathogen isolates and not to others and is relatively simply inherited.
A plant variety that exhibits a high degree of resistance to a single race, or strain, of a pathogen is said to be vertically resistant; this ability usually is controlled by one or a few plant genes.

Alternate host of black rust is Barberry.
Rust diseases that require two host plants to complete the life cycle generally have what is known as an economic host and an alternate host. The economic host, of these diseases, is wheat. The alternate host is typically a weed or native plant.
Wheat is the primary host, and barberry is the alternate host. The rust is sometimes termed "red rust" or "red dust" owing to the spores on the leaf surfaces that range from orange to dark red. Later, the spores change and become dark in colour, which gives rise to another common name, "black rust".

A. Hypertrophy : abnormal increase in the size of organ
Hypertrophy is an increase in cell size and volume. If enough cells of organ hypertrophy the whole organ will increase in size. Hypertrophy may involve an increase in intracellular protein as well as cytosol and other cytoplasmic components.
B. Hyperplasia : abnormal increase in the number of cells in the organ Hyperplasia is an increase in the number of cells in an organ or tissue that appear normal under a microscope.
C. Atrophy : inhibition of growth or dwarfing
Atrophy is a decrease in size of a body part, cell, organ, or other tissue. The term implies that the atrophied part was of size normal for the individual, considering age and circumstance, before the diminution.
D. Necrosis : death of plant is not correctly matched.
Necrosis is the condition when plants or plant cell cultures are subjected to abiotic stress they initiate rapid cell death with necrotic morphology.

Single super phosphate contains 16 - 20% P₂O₅.
It contains 3 major plant nutrients namely Phosphorus, Sulphur and Calcium along with traces of many micro-nutrients.
Traditional routes for extraction of phosphate rock using sulfuric acid give single superphosphate, an approximate 1 : 1 mixture of Ca(H₂PO₄)₂ and CaSO₄ phosphogypsum).
It consists of approximately 16 - 20% of phosphorus and 11% of sulphur.