CBSE Class 7 Marking Scheme 2022 Science Term 2 Set 3

TERM II SAMPLE PAPER - 3 MARKING SCHEME SUBJECT – SCIENCE CLASS - VII S.NO ANSWER MARKS 1 c) Both a and b 1 2 a) speedometer 1 3 d) all of these 1 4 b) ISI 1 5 c) Tuberculosis 1 6 b) lion 1 7 d) Kerosene 1 8 b) Fight against germs 1 9 c) 1 and 3 1 10 b) leaves 1 11 Plants absorb carbon dioxide from atmosphere for photosynthesis and release oxygen. 2 Thus they help to maintain the balance in the oxygen and carbon dioxide levels in atmosphere. That is why forests are called green lungs 12 Uniform motion can be defined as the motion in which a body travels equal distance in 2 equal intervals of time. Non-uniform motion can be defined as the body that covers unequal distances in equal intervals of time or equal distances in unequal intervals of time 13 A fuse is a safety device which prevents damage to electrical circuit and possible fires 2 In all buildings cruise are inserted in all electrical circuits there is a maximum limit of the current which can safely flow through the circuit if by accident the current exceeds this self-limit the wires may become over heated and may cause fire if a proper fuse is there in the circuit it will blow off and break the circuit as safety measure. 14 We are consuming more groundwater for industrial agricultural and as human waste 2 and on the other hand we are allowing lesser water to seep into the ground due to this reason depletion of water table occurs 15 Real image 2 Formed when reflected or refracted rays actually meet at a point Can be taken on a screen It is always inverted Virtual image Formed when reflected or refracted rays seems to come from a point Cannot be taken on a screen It is always erect 87

16 There are seven different colours in a rainbow though it may not be easy to distinguish 2 all of them they are as VIBGYOR and the colours are red, orange, yellow, green,blue, indigo and Violet 17 The trees have crowns of different types and sizes they create different horizontal 2 layers in the forest they are known as understoreys. Giant and tall trees constitute the top layer, followed by shrubs and tall grasses and herbs from the lowest layer 18 In sexual reproduction the male and the female gametes fuse to form a zygote for 2 sexual reproduction one or two parents are required to produce two different gametes and ultimately after zygote formation new individual forms. 19 The two upper chambers of the hearts are called the Atria and the two lower 2 chambers are called the ventricles 20 21 sanitation is the hygienic means of promoting health through prevention of hazards of 4 wastes as well as the treatment and proper disposal of savage waste water poor sanitation is a major cause of diseases worldwide and improving sanitation is known to have a significant beneficial impact on household and across communities so poor sanitation and contaminated water is the cause of a large number of diseases 22 The transfer of pollen grains from the anthers to the stigma of a flower is called 4 pollination If the pollen lands on the stigma of the same flower it is called self pollination when the pollen of a flower lands on the stigma of another flower of the same plant or the other plant of the same species is called cross pollination 88