Saturday, June 16, 2012

IX Biology:Extra marks Guess Solved Question paper : Cell and its Function

IX The Cell & Fundamental Unit of life
Q. Why is the cell known the 'fundamental and structural unit of life '

Ans: ell is called as the structural and functional unit of the living organism because it the smallest living entity that is capable of an independent existence. Separated cell organelles cannot be said to be living and are not capable of independent existence.
Q, what is a semi permeable membrane? what are the differences between semi permeable membrane and selectively permeable membrane?
Ans: a semi permeable membrane is a membrane that allows only the entry of substances that are helpful for the body. a semi permeable membrane is also called a selectively permeable membrane.
Q. Which cell in the human body does not have the mitochondria?
Ans: Mature erythrocytes don't have mitochondria
Q.What are plastids? Write their functions?
Plastids are double membrane organelles which are found in plant cells only.
Functions: 1. By trapping solar energy, green plastids manufacture food through photosynthesis
2. Chloroplasts provide colored to various flowering parts.
3. Leucoplasts help in storage of protein, starch and oil
Q. which structure of animal cells forms the asters of spindle ?
Ans: Centrioles.
Q. Name two semi- autonomous organelles?
Ans: Chloroplast and mitochondria
Q. Which cell organelle is rich in acid hydrolases?
Ans: Lysomes are loaded with acid hydrolases
Q. Which cell organelles are called ribonucleoprotine particle?
Ans: Ribosome.
Q. Differentiate between SER and RER  
Ans: Rough endoplasmic reticulum[RER] has ribosomes attached to it giving a rough appearance thereby deriving its name.  RER- involved in protein synthesis as ribosomes are concerned with protein synthesis.
Smooth endoplasmic reticulum [SER] is devoid of ribosomes.   SER-concerned with lipid synthesis in intestinal cells and with steroid formation in adrenals
Q. what is the difference between eukaryotes and prokaryotes?
Ans:
Prokaryotes
Eukaryotes
They are mainly unicellular
They are mainly multicellular except for protista
They have only a few organelles
Many organelles
DNA is circular
DNA is linear
DNA lies in the cytoplasm (Nucleus absent)
DNA is inside the nucleus
Cell division occurs mostly through binary fission
Mitosis, meiosis or both take place.

Q .What is the difference between osmosis and diffusion.
Ans:
Osmosis
Diffusion
It is the movement of water.
It is the movement of solute particle.
Membrane is required
Membrane is not required.
Movement from low concentration to high concentration of solute.
Movement from high concentration to low concentration of solute.
It is associated with liquids.
It is associated with both liquid and gases
Q. Differentiate Between  : Plant cell and animal cell
Ans: Plant cell
a)    have chloroplasts and use photosynthesis to produce food.
b)    have cell wall made of cellulose.
c)     A plant cell has plasmodesmata - microscopic channels which traverse the cell walls of the cells.
d)    one very large vacuole in the center.
e)    are rectangular in shape.
Animal cell
a)    don 't have chloroplast.
b)    no cell wall (only cell membrane).
c)     No plasmodesmata.
d)    one small vacuole.
e)    either circular, irregular or defined shapes depending on the type of cell.
Q. Where are peroxisomes found ?
Ans: Peroxisomes are small, living, membrane bound, sac like cell organelle found in photosynthetically active cells of plants, liver and kidneys. These are meant for removing toxic substances from the cell by oxidative reactions. These are also involved in photorespiration in plants.
Q. what are the chemical reactions take place in cytoplasm, nucleoplasm, and in mitochondria?
Ans: 1. Cytoplasm- Reactions of glycolysis.
2. Mitochondria- Reactions of Kreb's cycle.
3. Nucleoplasm- Reactions involving formation of RNA.
Q. what is Diffusion?
Ans: Diffusion is a spontaneous movement in which a substance moves from its region of higher concentration to the region of lower concentration. For example, in the case of a perfume, it moves from the region of higher concentration to lower concentration. So, it is a type of diffusion.
Q . What is dictyosomes ?
Ans: Dictyosomes are membranous or vesicular structures making up the Golgi apparatus. They together with golgi vesicles form the golgi apparatus .

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