7th Science - First Term Examination 2024
Summative Assessment - Science | Class 7 | Marks: 60 | Time: 2.00 Hrs.
I. Choose the correct answers. (8x1=8)
1. Which of the following is a derived quantity?
2. How can we increase the stability of an object?
3. An element which is always lustrous, malleable and ductile is
4. Nucleons comprises of _______.
5. Asexual reproduction in yeast is _______.
6. Climbing roots are seen in
7. Our living place should be
8. Which software is used to create symbols?
II. Fill in the blanks. (5x1=5)
9. The area of a leaf can be measured using a ______.
10. The rate of change of velocity is ______.
11. The ______ revolve around the nucleus.
12. After fertilization the ovule becomes ______.
13. I am green colour box with garbage. I am ______.
III. Say true or false, If false correct the statement. (5x1=5)
14. The region covered by the boundary of a plane figure is called its volume.
Correct Statement: The region covered by the boundary of a plane figure is called its area.
15. Argon is monoatomic gas.
16. Ginger is an underground root.
Correct Statement: Ginger is an underground stem (rhizome).
17. All food should be covered.
18. The nucleus is surrounded by protons.
Correct Statement: The nucleus is surrounded by electrons.
IV. Match the following. (5x1=5)
| Question | Answer |
|---|---|
| 19. Length | d) Rope |
| 20. Centre of gravity of geometrical shaped objects | a) Large base area (related to stability) |
| 21. Hydrogen | b) Monovalent |
| 22. Hook | e) Bignonia |
| 23. Animation | c) Visual Communication |
V. Complete the analogy. (3x1=3)
24. Displacement/Time : Velocity :: Distance/time : ______
25. K : Potassium :: C : ______
26. Tuberculosis : Air :: Cholera : ______
VI. Short answers (any seven) (7x2=14)
27. What are derived quantities?
28. Distinguish speed and velocity.
- Speed: It is the rate of change of distance. It is a scalar quantity (has only magnitude). Formula: Speed = Distance / Time.
- Velocity: It is the rate of change of displacement. It is a vector quantity (has both magnitude and direction). Formula: Velocity = Displacement / Time.
29. Classify the following as elements and compounds.
i. Water, ii. Common salt, iii. Sugar, iv. Carbon dioxide, v. Iodine, vi. Aluminium
- Elements: Iodine, Aluminium
- Compounds: Water, Common salt, Sugar, Carbon dioxide
30. What is atomic number?
31. The atomic number of an element is 9. It has 10 neutrons. Find the element from the periodic table. What will be its mass number?
- The element with atomic number 9 is Fluorine (F).
- Mass Number = Number of Protons + Number of Neutrons
- Mass Number = 9 + 10 = 19.
32. Write two types of reproduction in plants.
- Asexual Reproduction: Reproduction without the involvement of gametes (e.g., budding, fragmentation, vegetative propagation).
- Sexual Reproduction: Reproduction involving the fusion of male and female gametes.
33. What is hygiene?
34. Name the mode of transmission of communicable diseases.
- Through contaminated air (Air-borne diseases).
- Through contaminated water and food (Water-borne diseases).
- Through vectors like insects (Vector-borne diseases).
- Through direct contact with an infected person.
35. Write a note on 2D and 3D pictures.
- 2D (Two-Dimensional) Pictures: These have only two dimensions: length and width. They appear flat and lack depth. Examples include drawings on paper, photographs, and shadows.
- 3D (Three-Dimensional) Pictures: These have three dimensions: length, width, and depth (or height). They have a sense of volume and look realistic. Examples include sculptures, holograms, and objects we see in the real world.
VII. Answer in detail (any four) (4x5=20)
36. How will you determine the density of a stone using a measuring jar?
- Measure the Mass: Use a physical balance to accurately measure the mass of the stone. Let the mass be 'm' grams.
- Measure the Volume (Water Displacement Method):
- Take a measuring jar and fill it partially with water.
- Note the initial volume of the water (V1).
- Gently tie the stone with a thread and immerse it completely into the water in the measuring jar.
- The water level rises. Note the final volume of the water (V2).
- The volume of the stone is the difference between the final and initial water levels. Volume of stone (V) = V2 - V1.
- Calculate the Density: Use the formula for density.
Density (ρ) = Mass (m) / Volume (V).
The unit of density will be g/cm³ or g/ml.
37. Explain the types of stability with suitable examples.
- Stable Equilibrium: An object is in stable equilibrium if its centre of gravity is at the lowest possible position. When slightly displaced, it returns to its original position.
Example: A cone resting on its base. If you tilt it, it comes back to its original position. - Unstable Equilibrium: An object is in unstable equilibrium if its centre of gravity is at the highest possible position. When slightly displaced, it topples over and does not return to its original position.
Example: A cone balanced on its tip. A small push will make it fall. - Neutral Equilibrium: An object is in neutral equilibrium if its centre of gravity remains at the same height when it is displaced. It will stay in the new position.
Example: A ball or a cone lying on its side. If you roll it, it stops in a new position but does not topple.
38. Explain the characteristics of compound.
- Chemical Combination: A compound is formed when two or more elements combine chemically in a fixed ratio by mass. For example, in water (H₂O), hydrogen and oxygen are always in a 1:8 ratio by mass.
- New Properties: The properties of a compound are entirely different from those of its constituent elements. For example, hydrogen and oxygen are gases, but their compound, water, is a liquid.
- Homogeneous Nature: A compound is a pure substance and is homogeneous, meaning it has a uniform composition throughout.
- Separation: The constituents of a compound cannot be separated by physical methods. They can only be separated by chemical reactions.
- Energy Change: The formation of a compound usually involves an energy change, such as the release or absorption of heat or light.
- Fixed Melting and Boiling Points: A pure compound has a definite melting point and boiling point.
39. The atomic number and mass number of an element is 26 and 56 respectively. Calculate the number of electrons, protons and neutrons in its atom. Draw its atomic structure.
- Atomic Number (Z) = 26
- Mass Number (A) = 56
- Number of Protons = Atomic Number (Z) = 26.
- Number of Electrons = Number of Protons (in a neutral atom) = 26.
- Number of Neutrons = Mass Number (A) - Atomic Number (Z) = 56 - 26 = 30.
Diagram of Atomic Structure
1. Draw a central nucleus.
2. Inside the nucleus, write: 26 Protons (p+) and 30 Neutrons (n⁰).
3. Draw concentric circles (shells) around the nucleus.
4. Distribute the 26 electrons in the shells:
- 1st shell (K-shell): 2 electrons
- 2nd shell (L-shell): 8 electrons
- 3rd shell (M-shell): 14 electrons
- 4th shell (N-shell): 2 electrons
40. Draw the L.S. of a flower and label its parts.
Diagram of L.S. of a Flower
A diagram showing the longitudinal section of a typical flower (like a hibiscus) should be drawn here. The following parts must be clearly labeled:
- Pedicel: The stalk of the flower.
- Thalamus (or Receptacle): The base of the flower on which other parts rest.
- Calyx (Sepals): The outermost green, leaf-like whorl.
- Corolla (Petals): The colorful whorl inside the calyx.
- Androecium (Stamen): The male reproductive part, consisting of:
- Anther: Produces pollen grains.
- Filament: The stalk supporting the anther.
- Gynoecium (Pistil/Carpel): The female reproductive part, consisting of:
- Stigma: The receptive tip for pollen.
- Style: The tube connecting the stigma to the ovary.
- Ovary: Contains the ovules.
41. Write about any three communicable diseases in detail.
- Causative Agent: Bacterium called Mycobacterium tuberculosis.
- Mode of Transmission: It is an air-borne disease that spreads through droplets from the cough or sneeze of an infected person.
- Symptoms: Persistent cough, fever, chest pain, weight loss, and night sweats.
- Prevention & Control: BCG vaccination, keeping a safe distance from infected individuals, and ensuring good ventilation.
- Causative Agent: Bacterium called Vibrio cholerae.
- Mode of Transmission: It is a water-borne disease that spreads through the consumption of contaminated food or water.
- Symptoms: Severe watery diarrhea, vomiting, muscle cramps, and rapid dehydration.
- Prevention & Control: Drinking boiled or purified water, maintaining personal and community hygiene, and proper disposal of sewage.
- Causative Agent: A protozoan called Plasmodium.
- Mode of Transmission: It is a vector-borne disease, transmitted by the bite of an infected female Anopheles mosquito.
- Symptoms: High fever with chills, headache, vomiting, and sweating.
- Prevention & Control: Using mosquito nets and repellents, preventing water stagnation to stop mosquito breeding, and spraying insecticides.