Assertion : In woody stems, the amount of heart wood continues to increase year after year.
Reason : The cambial activity continues uninterrupted.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
A.
If both assertion and reason are true and reason is the correct explanation of assertion
Heartwood formation occurs spontaneously because it is a genetically programmed process. As a result of continued secondary growth for several years, the older parts of the stem and its old branches have a part of its secondary xylem rendered non - functional. Therfore, heart wood is a modified or non- functional secondary xylem. It is also known as duramen. Sap wood is the functional outer younger rings of secondary xylem. It is also known as alburnum. With the passage of time and addition of new outer rings of secondary xylem due to cambial activity more rings ofthe sap wood are changed into heart wood. This leads to the increase in the thickness of heart wood, whereas the sap wood remains of about the same thickness.
Assertion: In angiosperms, transport of food and water is more efficient than gymnosperms and pteridophytes.
Reason: In angiosperms longitudinally arranged sieve elements and vessels with perforated end walls are present.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false.
Assertion : Petroplants produce large amount of latex.
Reason : The latex contains long chain hydrocarbons.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
Which one of the following statements pertaining to plant structure is correct?
Cork lacks stomata, but lenticels carry out transpiration.
Passage cells help in transfer of food from cortex to phloem
Sieve tube elements possess cytoplasm but no nuclei.
The shoot apical meristem has a quiescent centre
Plasmodesmata connections help in
cytoplasmic streaming
synchronous mitotic divisions
locomotion of unicellular organism
movement of substances between cells
The quiescent centre in root meristem serves as a
site for storage of food which is utilized during maturation
reservoir of growth hormones
reserve for replenishment of damaged cells of the meristem
region for absorption of water
Assertion : Water and mineral uptake by root hairs from the soil occurs through apoplast until it reaches endodermis.
Reason : Casparian strips in endodermis are suberized
If both Assertion and Reason are true and the reason is the correct explanation of the assertion
If both Assertion and Reason are true but the reason is not the correct explanation of the assertion
If Assertion is true statement but Reason is false
If both Assertion and Reason are false statements
In a dicotyledonous stem, the sequence of tissues from the outside to the inside is
phellem - pericycle - endodermis - phloem
phellem - phloem - endodermis - pericycle
phellem - endodermis - pericycle - phloem
pericycle - phellem - endodermis - phloem
When does a plant wilt?
When phloem is blocked
When xylem is blocked
Pith is removed
A few leaves are removed
