Chapter 3 cell structure and function short Questions

 Q.NO 1 why lysosomes are called suicidal sacs?

ans: Lysosomes are capable of digesting nucleic acid, polysaccharides, fats, and proteins because they contain many different digestive enzymes. Along with them lysosomes also digest or damage its own cells by its own enzymes, which lead to cell death when the membrane of lysosomes is ruptured and enzymes are set free. This process is called as autolysis. Hence lysosomes are also called as suicide bags or suicidal sacs.

Q.NO 2 why plasma membrane is differentially permeable in nature?

Ans: Plasma membranes or cell membranes are differentially permeable or semi permeable to control the movement of substances into and out of the cells. They allow free diffusion of water and other non-ionic small molecules while preventing the diffusion of charged and large sized particles like glucose, amino acids and solutes etc, these large sized particle enter by the process of facilitate diffusion

Q.NO 3 why plant cell wall is rigid?

Ans: plant cell wall is rigid because it contain the cellulose fibers in it and the arrangement of cellulose fiber which is criss crossed.

Cellulose fibers along with other compounds also make cell wall hard and stiff like lignin and calcium pectate

Q.NO 4 why chloroplast is called energy converting cell organelle?

Ans: chloroplast contain chlorophyll which is the pigment responsible to capture light energy this light energy is used to make other energy rich compounds like ATP and NADPH2 during the process of photosynthesis, these compounds release chemical energy hence chloroplast convert light energy into chemical energy. That is why chloroplast is called energy converting cell organelle.

Q.NO 5 how prokaryotic ribosome is different from eukaryotic ribosome

Ans : There is the size difference in prokaryotic and eukaryotic ribosomes. The ribosomes in a eukaryotic cell generally have a Svedberg value of 80S and are comprised of 40s and 60s subunits. Prokaryotic cells, on the other hand, contain 70S ribosomes, each of which consists of a 30s and a 50s subunit

Q.NO 6 how mitochondria is similar to bacteria? 

Ans: 1) mitochondria are similar to bacteria in size and shape. 

2) Mitochondria have their own DNA that is highly related to bacterial DNA. 

3) Mitochondria divide by fission. 

4) mitochondria have ribosomes, similar to those found in bacteria, allowing them to synthesize some of their own proteins.

Q.NO 7 why mitochondria is called the powerhouse of the cell?

Ans: Mitochondria are cell organelles present in the eukaryotic cells. They are involved in the cellular respiration. They releases energy from food. They generate energy rich molecules, ATP from cellular respiration which is later used for other process. Hence, mitochondria are called as the powerhouses of the cell

Q.NO 8 differentiate between peroxisomes and glyoxysomes. 

                        

                          Peroxisomes

1) Peroxisomes are single membrane microbodies found in photosynthetic cells of plants, liver and kidney cells of vertebrates

2) it contain enzymes like catalase, oxidase and peroxidase enzyme

3) it is involved in the formation of hydrogen peroxide from alcohol and then conversation of hydrogen peroxide into water means it causes detoxification

                          Glyoxysomes

1) glyoxysomes are single membrane microbodies found in plant cells only

2) it contain enzymes like isocrates lyase and glycolate oxidase enzyme etc

3) it is involved in photorespiration the conversation of fatty acids into carbohydrates in germinating seed