Q-1. What is function of sieve tubes and companion cells?
Q-2. Where is columnar epithelium present in our body.
Q-3. Name and explain all the components of xylum.
Q-4. Give exa of a fluid connective tissue and explain.
Q-5. What are the roles of sclerenchyma?
Answers
Answer:
1.) Sieve tube members do not have ribosomes or a nucleus and thus need companion cells to help them function as transport molecules. Companion cells provide sieve tube members with proteins necessary for signaling and ATP in order to help them transfer molecules between different parts of the plant.
2.) In humans, a simple columnar epithelium lines most organs of the digestive tract including the stomach, small intestine, and large intestine. Simple columnar epithelia line the uterus.
3. )The structural elements of xylem are tracheids, vessels or tracheae, xylem fibres, xylem parenchyma and rays. The tracheid is derived from a single cell and can be regarded as the basic cell type of xylem tissue.
4). Fluid Connective Tissue
Blood and lymph are fluid connective tissues. Cells circulate in a liquid extracellular matrix. The formed elements circulating in blood are all derived from hematopoietic stem cells located in bone marrow (Figure 4.3. 6 – Blood: A Fluid Connective Tissue).
5.) Sclerenchyma tissue, when mature, is composed of dead cells that have heavily thickened walls containing lignin and a high cellulose content (60%–80%), and serves the function of providing structural support in plants. ... Fibers are very elongated cells that can be found in stems, roots, and vascular bundles in leaves.
Explanation:
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