Cell the unit of life
short answer type questions
1. It is said that the Protoplasm cannot be analysed chemically.
Ans - It cannot be analysed chemically because the chemical composition of Protoplasm is very complex and it ceases to be Protoplasm as soon as it is removed from an organism.
2. What is the difference between organ and organelle?
Ans- Several tissues contributing to some specific function inside the body considered an Organ where is the living structures present in the cytoplasm which perform a specific function is called cell Organelle.
3. Do you think that the cells of an elephant would be larger than the cells of a rat. why?
Ans- Larger organisms do not have large cells but they have greater number of cells .Small organisms have less number of cells.
4. Differentiate between the following
(a) Protoplasm and Cytoplasm.
Ans-
i. Protoplasm is a translucent living substance of a cell whereas Cytoplasm is a viscous semi-transparent Jelly like substance present in the cell.
ii. Protoplasm includes nucleus whereas Cytoplasm excludes nucleus.
(b) Nucleolus and Nucleus.
Ans-
i. Nucleolus is present in the nucleus whereas Nucleus is an organelle present in the cytoplasm.
ii. Nucleolus helps in protein synthesis whereas Nucleus controls the transmission of hereditary characters from parents to offspring.
(c) Centrosome and Chromosome.
Ans-
i. Centrosome is an organelle present near the nucleus whereas Chromosome is a thread like structure present in the nucleus.
ii. Centrosome initiates cell division in animal cell whereas Chromosome helps in the transmission of hereditary characteristics from parents to the offspring.
iii. Centrosome contain Centrioles. whereas chromosome contains DNA .
(d) Cell wall and Cell membrane.
Ans-
i. Cell wall is the outer covering of plant cell whereas Cell membrane is the outer covering of animal cell.
ii. Cell wall is non living whereas Cell membrane is living.
iii. Cell wall is freely permeable whereas Cell membrane is semipermeable.
(e) Plant cell and Animal cell.
Ans-
i. Plant cell wall is made up of cellulose and is present whereas in Animals cell, cell wall is absent .
ii. In plant cell, centrosome is absent whereas In animal cell centrosome is present.
iii. In plant cell plastids are present In animal cell plastids are absent.
(f) Prokaryotes and Eukaryotes
Ans-
i. In prokaryotic cell the nuclear material is not enclosed by a nuclear membrane whereas In Eukaryotic cell a prominent nucleus membrane covers the nuclear material .
ii. Prokaryotic cell contains single chromosome whereas Eukaryotic cell contains more than one chromosome.
iii. In prokaryotic cell nucleus is absent whereas In Eukaryotic cell nucleus is present.
5. Mention three features found only in plant cells and one found only in animal cells.
Ans-
Plant cells
i. They have cell wall.
ii. They have plastids.
iii. Vacuoles are prominent.
Animal cell
i. Centrosome is present in animal cell.
6. Why are the cells generally of a small size?
Ans- Cells are generally of small size because of the following reasons :-
i. Different regions of a cell can communicate with each other rapidly for the cell to function effectively.
ii. Cell have a large surface area for a greater diffusion of substances in and out of the cell.
LONG ANSWER TYPE QUESTIONS
1. What is the cell theory who propounded it and when
Ans- The cell theory states three main points:-
i. The cell is the smallest unit of structure of all living things.
ii. The cell is the unit of function of all living things.
iii. All cells arise from preexisting cells.
The cell theory was propounded by Schwann and Schleiden in the year 1839.Later Rudolf Virchow also added one statement to it.
2. Mention any three differences between a living cell and a brick in a wall.
Ans-
i. Cell is living whereaa brick is non living.
ii. Cell shares material with neighbouring cells whereas break doesn't.
iii Cell has a definite lifespan whereas brick doesn't have.
3. Name the plastid and pigment likely to be found in the cells of:-
(a) Petals of sunflower -Chromoplast(Xanthophyll)
(b) Ripe tomato - Chromoplast(Lycopene)
(c) Skin of green mango - Chloroplast (Chlorophyll) -Chloroplast(chlorophyll)
(d) Cells of potato-Leucoplast(No pigment)
4. State the major functions of the following:-
(a) Plasma membrane - It is selectively permeable and maintains the internal environment of cell.
(b) Ribosome- They help in protein synthesis.
(c) Lysosome- It protects the body from the bacteria and removes and destroys the old worn out cell organelles.
(d) Mitochondria- It helps in cellular respiration.
(e) Golgi apparatus- This functions in secretion and formation of cell wall in plant cell .
(f) Cytoplasm -A number of chemical reactions take place in cytoplasm and they supply energy and also functions in storage of food material .
(g) Asters of centrosome -They initiate cell division in animal cells.
(h) Chromosomes - They determine the characteristics of an organism and transmits them from one generation to the other.
(i) Glycogen granule
(j) Vacuoles- They provide turgidity in Plant cell and also store food and waste materials.
5. List any six features found both and plant and animal cells.
Ans-
a. They boat contains cell membrane.
b. They both contains cytoplasm and nucleus.
c. They both contain endoplasmic reticulum.
d. They both contain Golgi bodies.
e. They both contain mitochondria.
f. They boat contain ribosomes.
IMPORTANT TERMS
1.Cytology- The branch of Biology which deals with the study of cells and their parts.
2. Organelles -The living components of the cells having definite structure and function.
3. Vesicle-A round or spherical body filled with solution containing materials like proteins for Transport within the cell or extracellular fluid.
4.Enzymes- These are the bio catalyst which alter the rate of a chemical reaction without undergoing any change.
5. Hormones- The secretion of an exocrine or endocrine gland.
6. ATP - ( adenosine triphosphate) the energy currency of a cell.
7. Genes- These are the hereditary units of a chromosome which are made up of DNA.
8.Vacuoles- These are the certain clear spaces in the cytoplasm .They are filled with water and various substances in solution . They contain a liquid called cell sap.
ADDITIONAL QUESTIONS
1.First person to observe the living cell -Anton van leeuwenhoek
2.The smallest cell- Mycoplasma
3. Bearer of heredity -chromosomes
4. A prokaryotic cell- bacterium
5. The suicide bag of the cell- lysosome
6.The powerhouse of the cell- mitochondria
7.The green coloured plastid- chloroplast
8. The plastid which provides yellow colour to the petals- chromoplast
9. The site of protein synthesis- ribosome
10.The kitchen of the cell- chloroplast
11.The scientist was observed cork cell and coined the term cell -Robert hooke
12. The term Protoplasm was first coined by - Purkinje
State the contributions of following scientists:-
1. Rudolf Virchow- He added to the cell theory that all cells arise from preexisting cells.
2. Anton van leeuwenhoek- The first microscope was constructed by him.
3.Theodar Schwann - A German zoologist mets discoveries and animals and declared that all animals and plants are composed of cells.
4. Matthias schleiden - A German botanist announced that every plant is made up of a large number of cells.
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