Class 9 Science Chapter 5 MCQ

Here, are all the statements are correct. Hence, your answer will be option [D].

The micrometer commonly known as micron in SI derived unit of length equaling to 10^-6 of a metre.

Unlike eukaryotic cell, a prokaryotic cell lacks membrane bound organelles like plastids, mitochondria and endoplasmic reticulum but smaller and randomly scattered ribosomes are seen.

Here, are all the statements are correct. Hence, your answer will be option [D].

Other than nucleus mitochondria contains DNA and are able to synthesise their own proteins they are regarded as semi-autonomous organelles.

If the medium surrounding the cell has a higher water concentration, than the cell will gain water by osmosis, such a dilute solution is called hypotonic solution.

Plasma membrane is present in cells of plants, animals and microorganisms.

Golgi body was first discovered by Camillo Golgi. Golgi bodies, or Golgi complex are formed by stacks of flattened (saucer-shaped) membranes or flattened sacs called cisternae. Golgi bodies are usually called dictyosomes in plants. Golgi apparatus is absent in bacteria, blue-green algae, mature sperms and red blood cells of mammals and other animals. The Golgi apparatus arises from the membrane of the smooth endoplasmic reticulum, which in turn originates from the rough endoplasmic reticulum. The proximal Golgi saccules (cisternae at cis face) are formed by fusion of ER-derived vesicles, while distal saccules (cisternae at trans face) “give their all” to vesicle formation and disappear. Thus, Golgi saccules are constantly and rapidly renewed. The main functions of Golgi apparatus are (i)They store, modify, package and condense the proteins synthesised in the ribosomes. (ii)They form the cell plate during the cell division. (iii)They set aside digestive enzymes in tiny membrane bound vesicles which later become lysosomes. (iv)They synthesise some polysaccharides for the cell membrane.

The movement of water molecules through selectively permeable membrane along concentration gradient is called osmosis. It is the passage of water from region of high-water concentration through semipermeable membrane to a region of low water concentration (only through semipermeable membrane). Unicellular freshwater organisms and most plant cells tend to gain water through osmosis. Absorption of water by plant roots is also an example of osmosis.

Ribosomes are dense, spherical and granular particles which remains freely in the matrix or remain attached to endoplasmic reticulum. They are not bound by membrane and are present in both prokaryotic and eukaryotic cells. They play important role in synthesis of proteins. All enzymes are proteins but all hormones are not proteins.