SUBJECTIVE & SHORT QUESTIONS OF ULTRASTRUCTURE

SUBJECTIVE QUESTIONS

  1. Describe structure and function of Endoplasmic reticulum.
  2. Write note on plastids?
  3. Describe structure of chloroplast.
  4. Describe structure and function of mitochondria.
  5. Write note on Dictyosome.
  1. Give structure and function of ribosome.
  2. Write note vacuoles.
  3. Write note peroxisomes.
  4. Write note Glyoxisomes.

SHORT QUESTIONS

What are SER? Give their function.

Ans: The cytoplasmic surface of the SER lacks ribosomes. So they are known as SER. SIR of various cell types functions in diverse metabolic processes like synthesis of lipids, carbohydrate metabolism, the detoxification of drug and other poisons.

  1. What is role of SIR in synthesis of lipids?

Ans:      Enzymes of the smooth FR arc important for the synthesis of

fats. phospholipids. steroids. and other lipids. they produce steroids. The steroids arc the sex hormones. The cells of the testes and ovaries are rich in smooth ER. ‘These cells synthesize and secrete steroid hormones.

  1. What is the role of RER in membrane production?

Ans: Rough ER is a membrane factory. It grows by adding proteins and phospholipids. They are inserted into the ER membrane itself. The eivymes present in the RER synthesize their membranes from these phospholipids and proteins. The ER membrane can he transferred into the cell membrane in the form of vesicles.

  1. What are plastids? Who did name them?

Ails: The membranous bound and pigment containing bodies present in the cell are called plastids. Name plastid sits lirst used by Schimper in 1883.

  1. What are protoplastids and etioplast?

Ans: The newly form plastid is called protophtstid. It then changes into etioplast. Itioplast grows to form complete plastids.

  1. What are chloroplasts?

Ans: The dembrane bound structure, containing green pigment chlorophyll is called chloroplast.

  1. What is number of .chloroplast in a cell?

Ans: A typical mesophyll cell contains about 30 to 40

chloroplasts. According to one observation, leaf of Ricinus contains 400,000 chloroplasts per square centimeter.

  1. What are the shapes of chloroplast?

Ans:     The shape of chloroplast is different in different species of

plants. Their shapes may be spheroid. ovoid or discoid. Some chloroplasts are vesicle like.

  1. What is stroma? Give its composition.

Ans:     Stroma is a fluid that surrounds the thylakoids. It covers

most of the volume of the chloroplast. It is gel like substance. It contains about 50 % of the chloroplast proteins. It contains proteins, sonic ribosomes and a small circular DNA.

10-What are grana? Give their composition.

Ans:     A granum is pile of thylakoids. stacked on each other like

coins. On the average. 50 or more thylakoids are piled to form one granum. ‘Hie light energy is trapped by the membranes of grana and ATP is synthesized.

11-What are chromplasts? Give their function.

Ans: The plastids containing coloured pigments other than chlorophyll are called chromolast. Chromoplalts give colour to plants other than green. Their shapes may be triangular or pyramidal or elliptical.

12-What are Amyloplasts, Aleuroplast and Lipoplast?

Ans: The starch storing leucoplasts are called amyloplasts. fhe protein storing leucoplasts are called aleuroplast. The lipid storing leucoplasts are called lipoplast.

13-What is mitochondria! matrix? Give its composition.


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Ans: The mitochondria) matrix is generally homogenous fluid. But sometimes it contains dense granules. It appears gel like. These granules contain phospholipids. The mitochondrial matrix also contains a circular DNA and ribosomes.

14-Name the enzymes present in the matrix of mitochondria.

Ans: Malate dehydrgenase, Citrate synthetase, a-keto acid dehydrgenase.

15-What are cis and trans faces of dictyosomes?

Ans: The cis face is located near ER. The trans face (or maturing face acts as the receiving and shipping departments of the Golgi apparatus.

16-Give two functions of dictysomes.

Golgi complex are concerned with cell secretions. For example in mammals, the pancreas secretes granules. These granules contain chi> mes that help in digestion. Golgi apparatus transport the proteins or enzymes outside the cell.

17-What is bound ribosome? Give their function.

Ans: They are attached to the outside of the endoplasmic reticulum. The proteins of bound ribosomes are stored in the inclusion of membranes. Or these proteins are exported from the cell. Some cells specialize in protein secretion like pancreas and other glands. These cells secrete digestive enzymes.

18-What are vacuoles?

Ans:      Vacuoles are compartments within the protop last bounded

by membrane tonoplast containing sap (aqueous solution). Vacuoles are present in both plant and animal cells. But they are most abundant in plant cells. In plants. they occupy major part of the cell.

19-Give two functions of vacuoles.

Ans:      They. expand the plant cells and do not dilute its cytoplasm.

They store water, cell products or metabolic intermediates. It also stores food reserves like protein. flavonoids, and alkaloids.

20-What are microbodies?

Ans:      Any of three distinct classes (peroxisomes, glyoxysomes.

and microperoxisomes) of cytoplasmic organdies that are bounded by a single membrane and contain a variety of enzymes is called microbody.

21-What are peroxisomes? Who did discover them?

Ans: Peroxisomes are cytoplasmic organelles. De-Duve and co­workers isolated peroxisome from liver cells and sonic other tissues. They are present in both animals and plants. They are also found in protozoa, yeast. and many types of cells of higher plant.

22-Name the enzymes present in peroxisomes.

Ans: They contain H202 — producing enzymes like oxidases and catalases. They also contain some oxidative enzymes like peroxidase, Catalase, glycolic acid oxidase and some other enzymes.

23-What are Glyoxisomes? Give their function.

Ans: Glyoxisomes are cytoplasmic organelles. These are present only in plant cells. These are most abundant in plant seedlings. Glyoxisomes, are present only for short period of germination of seed. These are present in lipid-rich seeds like castor oil and soybeans. These are absent in lipid-poor seed like pea.

24-Name enzymes present in Glyoxisomes.

Ans: They contain enzyme like glycolic acid oxidase, Catalase and number of other enzymes. ‘these enzymes are not present in animal cells.

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