Plant Pathology - Study Mode
[#791] In angiosperms, a mature male gametophyte is formed from a pollen mother cell through
Correct Answer
(C) One meiotic and two mitotic divisions
Explanation
Solution: 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.
[#792] Root pressure is maximum when
Correct Answer
(A) Transpiration is low, absorption high
Explanation
Solution: 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.
[#793] First reduction in pentose phosphate pathway is
Correct Answer
(C) Oxidation of glucose 6-phosphate
Explanation
Solution: 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.
[#794] Photophosphorylation is the process in which
Correct Answer
(A) CO 2 and O 2 unite
Explanation
Solution: Photophosphorylation is the process in which CO 2 and O 2 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.
[#795] Alternate host of black rust is
Correct Answer
(A) Barberry
Explanation
Solution: 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".