Following are the important questions and answers for cell and its structure. Students can prepare these questions and answers for their test and exams.
- What are SER? Give their function?
Ans: The cytoplasmic surface of the SER lacks ribosomes. So, they are known as SER. SER of various cell types functions in diverse metabolic processes like synthesis of lipids, carbohydrate metabolism, the detoxification of drug and other poisons.
- What is role of SER in synthesis of lipids?
Ans: Enzymes of the smooth ER are important the synthesis of fats, phospholipids, steroids. and other lipids. They produce steroids. The steroids are the sex hormones. The cells of the testes and ovaries are rich in smooth ER. These cells testes and ovaries are rich synthesize and secrete steroid hormones.
- 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 enzymes present in the RER synthesize their membranes from these phospholipids and proteins. The ER membrane can be transferred into the cell membrane in the of vesicles.
- What are plastids? Who did name them?
Ans: The membranous bound and pigment containing bodies present in the cell are called plastids. Name plastid was first used by Schimper in 1883.
- What are protoplastids and etioplast?
Ans: The newly form plastid is called protoplastid. It then changes into etioplast. Etioplast grows to form complete plastids.
- What are chloroplasts?
Ans: The membrane bound structure, containing green pigment chlorophyll is called chloroplast.
- 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 Ricimus contains 400,000 chloroplasts per square centimeter.
- 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.
- 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 some ribosomes and a small circular DNA.
- 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. The light energy is trapped by the membranes of grana and ATP is synthesized.
- What are chromoplasts? Give their function?
Ans: The plastids containing colored pigments other than chlorophyll are called chromoplasts. Chromoplasts give color to plants other than green. Their shapes may be triangular or pyramidal or elliptical.
- What are Amyloplasts? Aleuroplast and Lipoplast?
Ans: The starch storing leucoplasts are called amyloplasts. The protein storing leucoplasts are called aleroplast. The lipid storing lecoplast are called lipoplast.
- What is mitochondrial matrix? Give its composition?
Ans: The mitochondrial matrix is general 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.
- Name the enzymes present in the matrix of mitochondria?
Ans: malate dehydrogenase, Citrate synthetase, α-keto acid dehydrogenase.
- 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.
- Give two functions of dictygomes?
Ans: Golgi complex are concerned with cell secretions. For example, in mammals, the pancreas secretes granules. These granules contain enzymes that help in digestion. Golgi apparatus transport the proteins or enzymes outside the cell.
- 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.
- What are vacuoles?
Ans: Vacuoles are compartments within the protoplast 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.
- 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.
- What are microbodies?
Ans: Any of three distinct classes (peroxisomes, glyoxysomes, and microperoxisomes) of cytoplasmic organelles that are bounded by a single membrane and contain a variety of enzymes is called microbody.
- What are peroxisomes? Who did discover them?
Ans: Peroxisomes are cytoplasmic organelles. De-Duve and co-workers isolated peroxisome from liver cells and some other tissues. They are present in both animals and plants. They are also found in protozoa. yeasts and many types of cells of higher plant.
- Name the enzymes present in peroxisomes?
Ans: They contain H2O2 — producing enzymes like oxidases and catalases. They also contain some oxidative enzymes like peroxidase, Catalase, glycolic acid oxidase and some other enzymes.
- 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.
- 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.