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Tissues
Describe the structure of phloem.
Structure of Phloem. Phloem is a complex permanent tissue of the plant. The phloem consists of four types of elements: sieve tubes, companion cells, phloem fibres and the phloem parenchyma
The main conducting part of the phloem is sieve tube which is formed of elongated cylindrical cells arranged in vertical rows. The terminal walls of each sieve tube member has many minute pores through which food material passes very easily. The entire porous plate is termed as sieve plate. Each sieve tube member is supported by a long parenchymatous cell called the companion cell which helps the sieve tubes in the conduction of food material.
Phloem parenchyma formed of parenchymatous cells. They store the food material. Phloem also contains phloem fibres, also known as Bast Fibres.
A longitudinal section of phloem.
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How is a prokaryotic cell different from a eukaryotic cell?
What would happen if the plasma membrane ruptures or breaks down?
What would happen to the life of a cell if there was no Golgi apparatus?
Which organelle is known as the powerhouse of the cell? Why?
Where do the lipids and proteins constituting the cell membrane get synthesized?
How does an Amoeba obtain its food?
What is osmosis?
Carry out the following osmosis experiment:
Take four peeled potato halves and hollow each one out to make potato cups. One of these potato cups should be made from a boiled potato. Put each potato cup in a trough containing water. Now,
(a) keep cup A empty
(b) put one teaspoon sugar in cup B
(c) put one teaspoon salt in cup C
(d) put one teaspoon sugar in boiled potato cup D.
Keep this setup for two hours. Then observe the four potato cups and answer the following :
(i) Explain why water gathers in the hollowed portion of B and C?
(ii) Why is potato A necessary for this experiment?
(iii) Explain why water does not gather in the hollowed out portions of A and D.
By which instrument you can see internal structure of onion peel cell?
Do different organisms have different types of basic building units ? Briefly explain.
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