Tag: multicellular structure: tissue

Histogen theory (By Hanstein 1870) concludes that shoot apical meristem consists three distinct zones. 

A lenticel is mainly the opening present on the periderm of the secondarily thickened organs and the bark of woody stems and roots of dicotyledonous flowering plants. It is a porous tissue consisting of cells with large intercellular spaces. It helps in the direct exchange of gasses between the internal tissues and atmosphere through the bark, which is otherwise impermeable to gasses. Lenticels are found in most of the woody trees but absent is  woody climbers. If lenticels are blocked then root will die first due to lack of gaseous exchange. Thus, option C is correct.

A vascular bundle is a part of the transport system in vascular plants. The transport itself happens in vascular tissue, which exists in two forms: xylem and phloem. These are generally present in the veins of the leaf where the xylem channelizes the water and phloem conducts the prepared food from the source to the sink.

Bulliform cells  are so called because of its peculiar bubble shape. It mainly occurs on the upper surface of the leaves present in grasses. Water present in these cells helps to maintain its shape but loss of turgor pressure during the stress allows the leaves to roll up. During drought, the loss of moisture through vacuoles induces bulliform cells to cause the leaves of many grass species to close as the two edges of the grass blade fold up toward each other. Once adequate water is available, these cells enlarge and the leaves open again. Bulliform cells are present in only monocot leaf and absent in dicot leaf. 
Thus, the correct answer is option A.

Laticiferous vessels are the specialized thin walled parenchymatous cells that secrete latex and are found in the cortex. They lack pits and are composed of cellulose and hemicelluloses and serve to secrete latex. 

Vascular bundles of the plant show vascular cambium or cork cambium. Cork cambium is involved in making cork. Cork is a nonliving, water resistant tissue formed in many plants to prevent water loss. Cork cells are dead and have cell walls composed of a waxy substance "suberin" which is highly impermeable to gasses and water. This substance prevents the water loss from the stem. Cork also protects the plant from wear and tear. Hence, it is a protective type of tissue. Therefore, option A is correct.  

The epidermis is the outermost cellular layer which covers the whole plant structure, i.e. it covers roots, stem, leaves, flowers, and fruit. It is composed of a single layer of living cells. The outer walls, which are exposed to the atmosphere and usually thickened, are covered by a waxy, waterproof cuticle which is made up of cutin. The waxy cuticle prevents the loss of moisture from the leaves and stems. During drought, the plant hormone abscisic acid (ABA) triggers stomatal closure, thus reducing water loss.

Since the 1850s cytologists observed some granular structures in the cytoplasm of the living cells. These structures were originally named as sarcomas. The term mitochondrion was introduced by Carl Benda in 1898. The term mitochondrion became the widely used name for this organelle but still the term sarcosome is accepted to denote this organelle present in the muscle. Sarcosome is a large specialized mitochondrion found in a striated muscle fiber.
Thus, the correct answer is the option (A), 'Mitochondria'.

Involuntary muscles are those, which are not under our control. Diaphragm muscles are internal muscle, that divides the thorax and the abdomen and are involuntary. The walls of large organs like stomach, intestines, uterus and urinary bladder are involuntary.
Thus, the correct answer is option (C), 'Both (A) and (B)'.

Cardiac muscles are the muscles of the heart. They are self-contracting, autonomically regulated (meaning involuntary and must continue to contract in a rhythmic fashion for the whole life of the organism.
Thus, the correct answer is option (B), 'Cardiac muscles'.