CBSE Class 8 Science Cell Structure and Functions Worksheet Set A

Question. A patient with cancer of the food pipe, cannot eat and swallow. So to feed him, a tube is inserted directly into his stomach. Properly mashed food is now given to the patient directly through the pipe. Now that the food is going directly to the stomach instead of through the food pipe, which of these is likely to happen?
(a) water will not be absorbed
(b) the kidney will stop working
(c) carbohydrates will not be digested
(d) (no major problem will arise)

Answer. D

Question. The blood glucose level found in urine samples of 4 patients P, Q, R and X at periodic intervals after consumption of a glass of orange juice are shown in the graph below. (mg/dl - milligrams per decilitre)What is the patient X likely to be suffering from?

(a) Diabetes
(b) Anaemia
(c) High Cholesterol
(d) Hypertension

Answer. A

Question. A student is measuring the amount of oxygen produced from photosynthesis in a water plant, and hypothesizes that it is different for different colours of light. If her hypothesis is correct, which of these will VARY for different colours of light, assuming the starting setup for different colours is identical [figure 1]?

(a) the volume of the displaced water (X)
(b) the total volume of the water
(c) the temperature of the water
(d) the visible growth of the plant

Answer. A

Question. The percentage of which component INCREASES the most between inhaling and exhaling?
(a) Nitrogen
(b) Oxygen
(c) Carbon Dioxide
(d) Dust particles

Answer. C

Question. In the diagram shown below of the human urinary system, the function of separating urea from blood to form urine is carried out by the organ marked:

(a) A
(b) B
(c) C
(d) D

Answer. A

Question. In the diagram shown below, of the human urinary system, the function of separating urea from blood to form urine is carried out by the organ marked:

Answer. A

Question. Read the information and flowchart about blood groups and answers the question:Human blood is classified into different types. The main groups are A, B, AB and O. Every blood group is also classified by a rhesus factor which is positive or negative. Thus the blood groups are A+, A-, B+, B-, AB+, AB-, O+ and O-. Blood grouping is important because when our bodies are exposed to something foreign, like a blood transfusion, our immune system kicks in to protect us. One weapon the body uses for this is the production of antibodies, protein molecules released by plasma cells that bind to a specific antigen. The antibodies combine with the antigens on the surface of the invading cells and try to destroy the cells. A patient’s blood group is hence cross-matched with the donor’s blood group when giving blood transfusions, to prevent this kind of reaction, which can range from mild to very serious. This flowchart describes the process of identifying the different blood types:

(a) A+
(b) AB-
(c) O-
(d) There is an error in the results.

Answer. C

Question. Read the information and flowchart about blood groups and answers the question:<br><br>Human blood is classified into different types. The main groups are A, B, AB and O. Every blood group is also classified by a rhesus factor which is positive or negative. Thus the blood groups are A+, A-, B+, B-, AB+, AB-, O+ and O-. <br><br>Blood grouping is important because when our bodies are exposed to something foreign, like a blood transfusion, our immune system kicks in to protect us. One weapon the body uses for this is the production of antibodies, protein molecules released by plasma cells that bind to a specific antigen. The antibodies combine with the antigens on the surface of the invading cells and try to destroy the cells. A patient^s blood group is hence cross-matched with the donor^s blood group when giving blood transfusions, to prevent this kind of reaction, which can range from mild to very serious. This flowchart describes the process of identifying the different blood types:<br>[383_43_q.jpg]

(a) Germs that damage our bodies
(b) Molecules that help destroy foreign cells
(c) Cells that are used in blood transfusion
(d) Agents used in cross-matching of blood

Answer. B

Question. Study the diagram given here. In it, P could represent the mosquito, as it has 4 stages in its life cycle, it spreads diseases and it has wings. Which animals could letters Q, R and S represent?

(a) Q-Moth, R-Cockroach, S-Frog    
(b) Q-Frog, R-Firefly, S-Grasshopper
(c) Q-Moth, R-Firefly, S-Cockroach
(d) Q-Grasshopper, R-Sparrow, S-Housefly

Answer. C

Question. Mickey was observing the behaviour of ducklings. He saw that they followed their mother after hatching. He took a few ducklings as soon as they hatched and kept them in a separate pool, which had a fake duck. He found that the ducklings followed the fake duck. On the basis of this experiment, Mickey suggested the following explanations. Which of them could be true?

(a) Either a mother duck or a fake duck is required for the eggs to hatch.
(b) After hatching, the ducklings follow the first large moving object that they see.
(c) The ducklings would not have learnt to swim without the fake duck.
(d) The mother duck had instructed the ducklings to follow the fake duck.

Answer. C

Question. Jean-Baptiste Lamarck, a French natural historian, proposed a theory which said that if an organism acquires a character, it is passed on to its future generations. For example, Irfan's parents are thin and so will be Irfan. But if Irfan suddenly starts eating more and puts on weight, according to Lamarck's theory, he will pass on this character to his children and so they will also be fat.
A German biologist, August Weismann, did an experiment in which he cut off the tails of mice in 19 successive generations; yet each new generation was born with a tail, which could grow to its full length.
What can be concluded on the basis of these experiments?
(a) Weismann's experiment contradicted Lamarck's theory.
(b) Weismann's experiment supported Lamarck's theory.
(c) Weismann's experiment is not linked to Lamarck's theory
(d) Weismann's experiment was wrong.     

Answer. A

Question. Sanjay's mother noted his height regularly from the time he was very small. This graph shows his height at different ages. Study it and answer question.  This graph gives the height of Sanjay from which to which age?

(a) From birth to 5 years
(b) From 2 years to 5 years
(c) From 2 years to 10 years
(d) From 4 years to 8 years

Answer. A

Question. Sanjay's mother noted his height regularly from the time he was very small. This graph shows his height at different ages. Study it and answer question.
In which year shown in the graph did Sanjay's height increase the most?

(a) Between birth and the first year
(b) Between the first and second years
(c) Between the second and the third years
(d) Between the third and the fourth years

Answer. A

Question. Sunder and Shyam went to play outside in the hot sun during their summer holidays. After playing for a few hours, Shyam felt thirsty and extremely dizzy. What should he take to get okay?
(a) A cup of chocolate ice-cream with nuts
(b) A glass of water with glucose
(c) A glass of water with sugar and salt
(d) A glass of hot milk with sugar

Answer. C

Question. If a graph is plotted to show how the height of a normal human being changes with age, it is likely to look like:

Answer. D

Question. Centriole is associated with –
(A) DNA synthesis
(B) Reproduction
(C) Spindle formation
(D) Respiration
Answer. C

Question. The cell organelle associated with cell secretion is
(A) Plastids
(B) Mitochondria
(C) Golgi apparatus
(D) Nucleolus
Answer. C

Question. Which of the following is an inclusion?
(A) Mitochondrion
(B) Lysosome
(C) Golgi complex
(D) Starch grain
Answer. D

Question. Which of the following would not be considered part of a cell's cytoplsm?
(A) Ribosome
(B) Nucleus
(C) Mitochondrion
(D) Microtubule
Answer. B

Question. Which of the following is called the brain of the cell?
(A) Nucleus
(B) Mitochondria
(C) Ribosomes
(D) Plasma membrane
Answer. A

Question. Which one is not a part of nucleus?
(A) Chromatin
(B) Nucleolus
(C) Centrosome
(D) Nucleoplasm
Answer. C

Question. The common feature amongst nucleus, chloroplast and mitochondrion is –
(A) DNA
(B) Lamellae
(C) Cristae
(D) All of these
Answer. A

Question. Nucleus is separated from surrounding cytoplasm by a nuclear envelope which is –
(A) Single and porous
(B) Double and porous
(C) Single and nonporous
(D) Double and nonporous
Answer. B

Question. Nucleoplasm is continuous with cytoplasm through –
(A) Centriole
(B) Golgi apparatus
(C) Nuclear pores
(D) Endoplasmic reticulum
Answer. C

Question. Nucleolus was discovered by
(A) Fontana
(B) Schleiden
(C) Altmann
(D) Robert Brown
Answer. A

Question. The function of the nucleolus in the cell is
(A) Secretory
(B) Synthesis of DNA
(C) Synthesis of RNA and ribosomes
(D) None of these
Answer. C

Question. Which of the following phenomena is commonly referred as 'cell drinking'?
(A) Exocytosis
(B) Pinocytosis
(C) Endocytosis
(D) Phagocytosis
Answer. B

Question. The cell organelle taking part in photorespiration is
(A) Glyoxysome
(B) Dictyosome
(C) Peroxisome
(D) Endoplasmic reticulum
Answer. C

Question. Endoplasmic reticulum sometime contains –
(A) Ribosomes
(B) Lysosomes
(C) Golgi bodies
(D) None of these
Answer. A

Question. Ribosomes are composed of –
(A) 1 subunit
(B) 5 subunits
(C) 2 subunits
(D) 4 subunits
Answer. C

Questions

 Very Short Answer

Question. How the egg of a hen represents?
Answer. The egg of a hen represents a single cell.

Question. Who observed the slices of the cork under a simple magnifying device?
Answer. Robert Hooke observed the slices of the cork under a simple magnifying device

Question. What is cork?
Answer. Cork is the part of the bark of a tree.

Question. Who coined the term cell for each box?
Answer. Robert Hooke coined the term cell for each box.

Question. What is used to study the colour parts of the cell?
Answer. Stains are used to colour parts of the cell to study.

Short Answer

Question. What do you mean by cell?
Answer. The cell is the basic structural, functional, and biological unit of all known organisms. A cell is the smallest unit of life. Cells are the basic building blocks of all living things. The human body is composed of trillions of cells. Cells have many parts, each with a different function. Some of these parts, called organelles, are specialized structures that perform certain tasks within the cell.

Question. How do scientists observe and study the living cells?
Answer. Cells are studied by scientists under microscope or electron microscope. Cells or organism which cannot be seen through naked eyes are seen under microscope. Some cells or organisms are even smaller that it does not require a normal microscope.it is therefore seen through electron microscope.

Question. How Robert Hooke did discovered cells?
Answer. Hooke had discovered plant cells. Hooke saw were the cell walls in cork tissue. In fact, it was Hooke who coined the term cells the boxlike cells of cork reminded him of the cells of a monastery. Hooke also reported seeing similar structures in wood and in other plants.

Question. Why did Hooke use the term cells for the little box shaped structures he observed in Cork?
Answer. Hooke's drawings show the detailed shape and structure of a thinly sliced piece of cork. When it came time to name these chambers he used the word cell to describe them because they reminded him of the bare wall rooms where monks lived. These roomswere called cells.

Question. How many human cells are in the human body?
Answer. Humans are complex organisms made up of trillions of cells, each with their own structure and function. Scientists have come a long way in estimating the number of cells in the average human body. Human body has trillions of cells which vary in shapes and sizes.

Long Answer

Question. State the difference between amoeba and paramecium?
 Answer. 
1. Amoeba is a unicellular protozoan which moves by temporary projections called pseudopodia whereas paramecium is a single-celled freshwater animal with a characteristic slipper-like shape.
2. Amoeba is an irregular-shaped protozoan whereas paramecium is an oval-shaped protozoan.
3. Amoeba moves by forming pseudopodia whereas paramecium moves by beating the cilia.
4. Amoeba reproduces by asexual reproduction whereas paramecium reproduces sexually by conjugation in unfavourable conditions.
5. Amoeba is heterotrophs which use phagocytosis to engulf food particles whereas paramecium is a heterotroph which comprises an oral groove, gullet, and anal pore.

Question. Distinguish between onion cell and human cheek cell?
Answer. 
1. Onion cell is a plant cell whereas human cheek cell is an animal cell.
2. Onion cell has a cell wall made up of cellulose whereas human cheek cell does not have a cell wall.
3. Onion cell has a large vacuole whereas human cheek cell may have several, small vacuoles.
4. Onion cell has a brick-like, more regular shape whereas human cheek cell has a rounded shape.
5. Onion cells can be peeled off from an onion whereas human cheek cells can be scraped off from the inner oral cavity with the use of a toothpick.

Question. Write short note on cells?
Answer. A cell is defined as the smallest, basic unit of life that is responsible for all of life's processes. Cells are the structural, functional, and biological units of all living beings. A cell can replicate itself independently. All cells are made from the same major classes of organic molecules: nucleic acids, proteins, carbohydrates, and lipids. Cells are of two types: eukaryotic, which contain a nucleus, and prokaryotic, which do not. Prokaryotes are single-celled organisms, while eukaryotes can be either single-celled or multicellular. Cells are the basic building blocks of all living things. The human body is composed of trillions of cells. They provide structure for the body, take in nutrients from food, convert those nutrients into energy, and carry out specialized functions. Cells provide six main functions. They provide structure and support, facilitate growth through mitosis, allow passive and active transport, produce energy, create metabolic reactions and aid in reproduction.

Question. State the difference between multicellular and unicellular?
Answer. 
1. Unicellular organisms are composed of only one cell whereas multicellular organisms are composed from more than one cell.
2. In unicellular cell differentiation tissue forming are absent whereas in multicellular cell differentiation tissue forming are present.
3. In unicellular the number of cell is one whereas in multicellular the number of cells are more than one cell.
4. In unicellular the cellular organization can be observed whereas in multicellular there is no true cellular organization.
5. Unicellular can fix the atmospheric nitrogen whereas multicellular do not fix the atmospheric nitrogen.

Question. What are the advantages amoeba derive by changing the shape?
Answer. The advantages amoeba derive by changing the shape are:
1. They produce tentacle-like extensions called pseudopodia to move through their environments.
2. In open water an amoeba cell will form many pseudopodia in all directions as it floats this allows it to sense things at all angles.
3. When the encounter food they can grab or push the particles towards them for phagocytosis cell engulfing or eating of large particles.
4. During unfavourable conditions such as cold or dry times the amoeba will become a ball and secrete a protective membrane around itself to form a microbial cyst.
5. The cell remains in this protected state until more favourable conditions arise, it can die if it is unable to emerge for a long period of time.