Botany and Plant Science

Micropyle is the opening at the apex of ovule through which pollen grains enter the nucellus.

The basal portion of ovule just below the junction of the nucellus and integuments is called chalaza.

Megaspore mother cell produces 4 cells after meiotic division.

In orthotropous ovule, the funicle, chalaza and micropyle lie in a vertical line.

This type of ovule is present in family Leguminoseae.

Papaya is a dioecious plant with separate male and female individuals, so its seeds are unisexual. Bisexual flowers contain both male and female parts. Papaya produces male flowers on one plant and female flowers on another.

The ovary is the swollen basal part of the pistil that contains ovules, which are the future seeds. After fertilization, the ovary develops into the fruit while the ovules become seeds. The stigma receives pollen, the style is the pollen tube pathway, and anther lobes produce pollen - none contain ovules.

Autotetraploids (4x) can form when two unreduced diploid gametes (2n each) fuse during fertilization, producing a 4x zygote. This is different from chromosome doubling in somatic tissues. The fusion of two abnormal diploid gametes is one documented pathway to autotetraploidy in plants.

Apical meristems located at root and shoot tips are responsible for primary growth - increase in length through cell division and elongation. Lateral meristems (vascular cambium, cork cambium) cause secondary growth in girth. Intercalary meristems at nodes allow grass stems to elongate. The primary length increase comes from apical meristems.

Border parenchyma (also called bundle sheath extension) is a specialized layer of parenchyma cells that surrounds each vascular bundle in leaves. This layer connects the vascular bundle to both the upper and lower epidermis, facilitating transport and providing mechanical support. Palisade and spongy parenchyma are the main photosynthetic tissues, while chlorenchyma is a general term for chlorophyll-containing parenchyma.

The bundle sheath is a compact layer of thin-walled parenchyma cells that surrounds the vascular bundle in leaves. This sheath encloses both xylem and phloem tissues and plays a crucial role in photosynthesis, especially in C4 plants where it forms the Kranz anatomy. The bundle cap is distinct, endodermis is found in roots, and starch sheath is the innermost cortex layer.

In leaf anatomy, xylem is located towards the upper (adaxial) epidermis, while phloem is towards the lower (abaxial) epidermis. This dorsal-ventral arrangement is called amphistomatic leaf organization. The upper-side position of xylem facilitates efficient water delivery to the photosynthetic mesophyll cells. Bundle sheath surrounds the entire vascular bundle, and mesophyll is the photosynthetic tissue between the epidermal layers.

Monocot stems lack clear differentiation between cortex and stele because their vascular bundles are scattered throughout the ground tissue. In dicots and monocot roots, there's a distinct separation between cortex (outside the vascular cylinder) and stele (central vascular tissue). Monocot stems have numerous vascular bundles embedded in undifferentiated ground tissue without an endodermal boundary separating cortex from stele.

Statement (a) is wrong because it reverses the facts - maize is a monocot with polyarch xylem, while bean is a dicot with tetrarch xylem. Statement (b) is correct because xylem and phloem are radially arranged in roots. Statement (c) is correct because dicot roots typically have tetrarch xylem while monocot roots are polyarch.

Statement (a) is wrong because phloem parenchyma is absent in monocots and present in dicots. Statement (b) is correct - the starch sheath (endodermis) is present in dicot stems. Statement (c) is correct - hypodermis is collenchymatous in dicots and sclerenchymatous in monocots.