Describe the following structuresfunctions or cells Dermal v

Describe the following structures/functions or cells: Dermal, vascular, and ground tissues Root, stem, leaf - Monocot leaves and eudicot leaves Parenchyma, collenchyma, sclerenchyma, water-conducting cells of the xylem, and sugar-conducting cells of the phloem - Sieve-tube element and companion cell Explain the phenomenon of apical dominance Distinguish between determinate and indeterminate growth. Explain function of meristem. Describe and compare the three basic organs of vascular plants. Describe primary growth of stem and root and the formation of lateral roots. Distinguish between morphogenesis, differentiation, and growth Explain the ABC hypothesis of genetic control of flowering. Describe the use of Arabidopsis to understand plant development.

Solution

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2.Apical dominance is the phenomenon in which the main stem of the plant is dominant over the side lateral stems.The dominance is mainly due to the exclusive control of terminal bud present at shoot apex over the growth of lateral bud present in the lateral shoots.This allows the plant to grow only vertically.

3.Determinate growth means the growth continues till a structure is formed and stops after that while indeterminate growth never terminates and the growth continues.The meristem tissues undergo indeterminate growth and therefore function in active division of plant parts such as stem and roots.

4.The three basic organs of vascular plants are roots, shoot and leaves.Root consists of a root cap and root hairs to increase the surface area of absorption of water and minerals.Stem is the vertical axis of the plant that consists of nodes and internodes.It consists of three tissues, dermal,ground and vascular tissues.Leaves consists of upper and lower epidermis with a mesophyll layer in betwee them.There is an upper palisade layer and a lower spongy layer in the mesophyll.Presence of green pigment called chlorophyll present in the leaves to carry out photosynthesis.Roots function to absorb water and dissolve nutrients from the soil and help the plant to anchor in the soil. Stems provide support to the plant and and transport water and food throughout the plant. Leaves function in photosynthesis and gaseous exchange.

5.When there is an increase in the length of stem and the root of plant , it is known as primary growth. It results due to the division of cell present at the apical meristem of stem and roots.Lateral roots are formed by division of cells present in the pericycle of the xylem radius of the root.

6.Morphogenesis is the process by which an organism starts to develop its morphology i.e size,shape and structure while differentiation is the process by which cells or tissues or organs develop specialised characters the development process while growth is the process by which the cell increases in size.

7.According to the ABC hypothesis,there are 3 classes of genes known as A,B and C that are transcription factors required to form different whorls of the flower. A genes form whorls 1 and 2, B genes form whorls 2 and 3, and C genes form whorls 3 and 4. Both A and B genes are required to form whorl 2, and both B and C genes are required to form whorl 3.

8. Arabdiopsis development, reproduction, and response to stress and disease is similar to that of crop plants. Moreover, it produces many seeds and therefore extensive genetic experiments on plant develoment can be carried out.Also, Arabidopsis genome size is small and therefore genetic analysis can be done easily.It also lacks the repeated DNA sequences that usually bring complication in genome analysis.For all these reasons,Arabidopsis proves to be an ideal organism for studying developmen of plant.