“All cells arise from pre-existing cells” - who stated this?
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.
Which organelle releases energy?
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.
What is the full 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.
The passage of water from a region of higher water concentration through a semi–permeable membrane to a region of lower water concentration is:
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.
Which of the following is known as “physical basis of life”?
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.
Ribosomes are the centre for:
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.
Which of the following imparts colours to flower to attract insects for pollination?
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.
Which of the following is the largest cell organelle in plants?
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.
Find the incorrect statement:
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.
Bacteria can not survive in a highly salted pickle. Because
A particle covers equal distance in equal interval of time. It is said to be
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.
The rotational K.E of hoop is equal to the
The area under the velocity – time graph gives the
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.
The slope of distance – time graph gives instantaneous.
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.
Which of the following physical quantity is not present in first equation of motion?
Explanation:First equation of motion is v = u + at, so, in first equation of motion displacement is not present.
A body is travelling at a constant speed in a circle it has
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.
Which of the following is a false statement
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.
A body is moving with a velocity of 10m/s. If the motion is uniform, what will be the velocity after 10 second?
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.
What is the quantity which is measured as the area occupied in the velocity – time graph?
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.
A body is said to be in rest when
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.
According to ancient philosophers matter consists of
Explanation:According to ancient philosophers matter consists of five constituents (panchtatva). They are air, earth, fire, sky and water.
An Almirah is a solid because its
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.
The melting point of a substance is defined as the constant temperature at Atmospheric pressure when
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.
When acetone or nail polish remover is applied cooling is experienced due to which factor?
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.
Name the state of matter that ‘has minimum inter-particle force of attraction’
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
The inter-particle forces are the strongest in
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.
A desert cooler given comfort due to cooling caused by evaporation of water. Under which one of the following conditions it works more effectively?
The two major gases present in air are
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.
Identify the incorrect statement
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.
Which of the following statements is not true?
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.