Which among the following tissue is responsible for secondary growth?
Seive elements and trachieds are dead cells and they cannot undergo secondary growth. So, options C and D are invalid answers. Though mesophyl is a live tissue, they are not responsible for secondary growth. Cork cambium is a lateral meristematic tissue that is responsible for secondary growth that replaces the epidermis in roots and stems.
Which among the following chemical acts as the the photoperiodic stimulus from leaves to the flower-forming region?
"Option A is a wrong choice, because ethylene stimulates ripening of fruits. Option B is also a wrong choice, since giberrelins are known to increase length of stalk axis in grapes, cause fruits to elongate and improve their shape, and delay sensecence. Both the hormones do not have any significant role in flowering. There is no hormone called floragen identified in plants. So option C is the right answer. The photoperiodic stimulus travels from leaves to the flower forming region through phloem. This stimulus is in the form of a chemical called florigen. "
Which one increases in the absesnce of light?
In the absence of light stem become excessive long due to the develpoment of 'etiolin' which causes 'etiolation'. Cell of internodes get enlarged.
What reason will you assign for coconut milk used in tissue culture.
The medium in tissue culture provides all the essential nutrients required for growth and division of callus. Coconut milk contains cytokinins which is useful in tissue culture.
Which among the following effects is related to "water stress" in plants?
"Option C is the correct answer. When the moisture of soil is low, plants have to use more energy to absorb water from the soil. Thus the plants become stressed due to low moisture in soils. The amount of force that is needed by the plant to absorb water from the soil is called the matric potential. Due to water stress, matric potential becomes higher. This effect is called matric effect. "
Hormone primarily connected with cell division is
The most important function of cytokinins (zeatin is one of the cytokinins present in Zea mays-the corn) is the promotion of cell division. These are now established as true cell division factors.
Opening of floral buds into flowers, is a type of
Opening of floral buds into flowers, is a type of autonomic movement of growth which is due to epinasty.
In a plant, one can find high levels of cytokinins in
Natural cytokinins are found in the regions where rapid cell division occurs. Some of the plant regions where rapid cell division occurs are root apices, developing shoot buds, and young fruits.
The pigment, that absorbs red and far red light in plants, is
The pigment phytochrome is involved in flowering and many other light-mediated processes. It absorbs red and far red light in plants for photosynthesis.
The hormone that acts as a source of ethylene is
Ethaphon is a commercial compound that serves as source of ethylene. When ethapon is sprayed, it releases ethylene gradually. The released ethylene then hastens the ripening and maturation of fruits.
Why do plants have indefinite growth?
Option B is the correct answer. Meristematic cells are undifferentiated cells that are found in plant tips. They are capable of unlimited cell divisions thus making plants grow indefinitely.
Phytohormones are plant hormones which are synthesized by the plants and act as regulators and influlence physiological process like growth, movements etc. auxins, gibberellins etc. are the phytohormones.
Which among the following would show a high rate of elongation?
The growth velocity or the rate of elongation increases in the regions that move away from the apical meristems. The nodes and internodes are the regions in the plant that are away from the apical meristems, and the cells in the region are progressively expanding. Thus the cells elongate due to expansion. So option C is the correct answer.
Plants deficient of element zinc, show its effect on the biosynthesis of plant growth hormone
Zinc is one of the component of Auxin.
The maximum growth rate occurs in
The maximum growth rate occur in exponential phase.
If a tree, flowers thrice in a year(Oct., Jan. and July) in Northern India, it is said to be
In Northern India, during these months there is observed maximum variation in light intensity and duration and temperature. Hence only plants that are photo-and thermoinsensitive can flower during these monthes.
Which among the following pigments can affect ethylene synthesis in the plants?
Phytochrome is a light-absorbing pigment in plants that influences growth and flowering in plants. When the shoot is exposed to light, reactions by phytochrome in the plant's cells produce a signal for ethylene production to decrease. So, option A is the correct answer.
Which is employed for artificial ripening of banana fruits?
Ethylene is a plant hormone which has the most remarkable effect on stimulation of fruit ripening.
Cut or excised leaves remain green for long if induced to root or dipped in
Because cytokinins help cells in retaining chlorophyll for longer time. Cytokinin delay the senescence(ageing) of leaves an other organs.
Plant bends towards the light beacause
According to Went experiment, when monochromatic beam of light spread on Avena coleoptile then maximum growth took place on shaded side due to maximum IAA-synthesis .
Phytochrome is involved in
Borthwick & Hendricks (1952) gave the concept of phytochrome. Phytochrome is a coloured protein pigment located in plasma membrane to perceive the photoperiodic stimulus in leaves. It may exist in two interconvertable forms Pr and Pfr (red and far red light absorbing forms)
The response of different organisms to environmental rhythm of light and darkness is called
Photoperiodism is the effect of duration of light and darkness on the growth, development and behaviour of an organism.
Ethylene gas is used for
Ethylene is a gaseous plant hormone which plays an importatnt role in fruit ripening. In the presence of ethylene there is an increase in the rate of respiration.
A plant cell has potential to develop into a full plant. This is called
Any cell which has an ability to develop into a complete organism is totipotent.
The method that renders the seed coat permeable to water so that embryo expansion is not physically retarded is
Scarification is the breaking of the seed coat barriers which can be done by mechanical or chemical methods.
What is the effect of "pinching back" on house plants?
Pinching back is a method of removing the apical buds, thereby removing the source of auxin. Therefore, lateral buds grow, developing more branches, causing the plants become fuller and bushy. So option D is the correct answer.
Flowering dependent on cold treatment is
Vernalization is the method of inducing early flowering in plant by pretreatment of their seeds at low temperature.
Thigmotropism is the response of the plant to
Contact or friction with some object stimulates the movement of a plant part in a specific direction eg. tendril in the family- Cucurbitaceae.
which of the following hormones can replace vernalisation?
Vernalization is the low temperature treatment for flowering in plants. Plants are treated(seeds and seedlings) with very low temperature to promote germination.
What is wood?
Option C is the correct answer. Secondary xylem is otherwise called "wood". This is formed by the vascular cambium in the trunks of trees
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