Module 1 - MCQ Test, Science, Class 9 - Class 9 MCQ

Explanation:Rudolf Virchow presented the idea in 1855 that every cell arises from another (pre-existing) cell. This was a addition to the cell theory that was proposed earlier by Matthias Jakob Schleiden and Theodor Schwann.

Explanation:Mitochondria iscalled as power house of the cell because it contains enzymes for cellular respiration. During cellular respiration, energy is released which is stored in the form of ATP.

Explanation:The full form of ATP is adenosine triphosphate. ATP is known as the energy currency of the cell. The energy required for various chemical activities is released by mitochondria. They contain enzymes for cellular respiration.

Explanation:The passage of water from a region of higher water concentration to a region of lower concentration through a semi-permeable membrane is called osmosis. The movement of water across the plasma membrane is affected by the amount of substance dissolved in water.  

Explanation:According to Thomas Henry Huxley, the protoplasm is the physical basis of life. It is the living substance inside in the cell that contains all the cell organelles. It is a thick fluid or jelly-like substance.

Explanation:Protein synthesis involves formation of amino acid chain according to information present on the DNA. The ribosomes, which are present in all active cells, are the sites for the manufacture of proteins. The proteins manufactured by the ribosomes are sent to other organelles in the cell. Some proteins function as enzymes and hormones.

Explanation:Plant cells have plastids. Plastids with coloured pigments impart colours to various plant parts. Green colour is provided by chloroplast and other colours (except white) are imparted by chromoplast.

Explanation:Plastid is the largest cell organelle in a plant. It contains chlorophyll necessary for photosynthesis. Plastid is the site of manufacture and storage of important chemical compounds used by the plant cell.

Explanation:Plant cells can be larger than animal cells. Size of an animal cell varies from 10 to 30 micrometers while that of a plant cell ranges from 10 to 100 micrometers. 

Explanation:When a body covers equal distance in equal interval of time. It is said to be moving with constant speed. This type of motion is called uniform motion.

Explanation:The area under the velocity-time graph gives the displacement of the body. Which is equal to area of rectangle and area of triangle.

Explanation:The slope of a distance-time graph gives instantaneous speed of the moving object. Instantaneous speed can be more or less than average speed.

Explanation:First equation of motion is v = u + at, so, in first equation of motion displacement is not present.

Explanation:A body is travelling at a constant speed in a circular path. It has an inward radial acceleration. This kind of motion will produce centrifugal force.

Explanation:A body can have zero velocity and still be accelerated or constant speed and still have varying velocity but a body cannot have a constant velocity and varying speed.

Explanation:A body moving with uniform motion, never changes it speed. So, the velocity of the body remain same after 10 second that is 10m/s.

The area under the velocity time graph will give us the displacement of an object and the slope gives the acceleration

we should find the area under the graph , if the graph is irregular we need to split it into parts and finally add them and if the shape is not at all regular we should go for integration.

Explanation:When a body does not change its position with respect to time, it is said that body is in state of rest. Rest and motion are relative to observer.

Explanation:According to ancient philosophers matter consists of five constituents (panchtatva). They are air, earth, fire, sky and water.

Explanation:An almirah is solid because it is hard and rigid, have fixed shape and have very high density. All these properties are possessed by solid substance only.

Explanation:The constant temperature at which solid start changing into liquid at atmospheric temperature is called melting point. At this temperature, both the solid and liquid exist together.

Explanation:Evaporation causes cooling effect because the heat of evaporation is absorbed by the surroundings. Evaporation of acetone present in nail polish remover absorbs the latent heat from the nail Causing cooling of a  nail.

Explanation:The particles of gases are away from each other. So, gas has the minimum inter-particle force of attraction.Solids have maximum force of attraction

Explanation:Solids substances have the strongest inter-particle force of attraction. In the given substances, sodium bromide is solid, ethyl alcohol is liquid and ammonia and carbon dioxide are gases. So, the particles of Sodium bromide have the strongest force of attraction.

Explanation:Air is a mixture of gases. Two main constituents of air is  Nitrogen (78%) and Oxygen (21%). Other gases include carbon dioxide, helium, water vapour etc.

Explanation:Ether and Acetone is most volatile. Alcohol is moderately volatile and water is least volatile. So, the statement, Acetone is least volatile is incorrect statement.

Explanation:Anything that occupies space and have mass is called matter. Inter-particle space is maximum in the gaseous state of substance. The particles constitute zig-zag path and solid is most compact state of substance. Matter is not always continuous in nature.