Unit Test: The Invisible Living World: Beyond Our Naked Eye | Science Curiosity Class 8 - New NCERT PDF Download

Time: 1 hour

M.M. 30

Attempt all questions.

• Question numbers 1 to 5 carry 1 mark each.
• Question numbers 6 to 8 carry 2 marks each.
• Question numbers 9 to 11 carry 3 marks each.
• Question numbers 12 & 13 carry 5 marks each.
• 1-mark questions include MCQs.

Q1: The basic unit of all living organisms is the (1 Mark)
(i) tissue    
(ii) organ    
(iii) cell    
(iv) organ system

Q2: Which structure controls the activities inside a cell? (1 Mark)
(i) Cytoplasm    
(ii) Nucleus    
(iii) Cell membrane    
(iv) Cell wall

Cell

Q3: Onion peel cells appear rectangular and firm primarily because of the (1 Mark)
(i) nucleus    
(ii) vacuole    
(iii) chloroplast
(iv) cell wall    

Q4: Which is a correct level-of-organisation sequence in organisms? (1 Mark)
(i) Cell → Tissue → Organ → Organ system → Organism
(ii) Tissue → Cell → Organ → Organ system → Organism
(iii) Cell → Organ → Tissue → Organ system → Organism
(iv) Organism → Organ system → Organ → Tissue → Cell

Q5: Yeast makes dough rise mainly because it produces (1 Mark)
(i) oxygen  
(ii) nitrogen    
(iii) carbon dioxide    
(iv) ammonia

Rised Dough

Q6: State two differences between plant cells and animal cells seen at this level of study. (2 Marks)

Q7: Define microorganisms. Give one example each of a unicellular microorganism and a multicellular microorganism. (2 Marks)

MicroorganismsQ8: What are root nodules and how do the bacteria in them benefit crops? (2 Marks)

Q9: Explain how the structure of a nerve cell relates to its function. Contrast it briefly with a cheek cell. (3 Marks)

Q10: During the onion peel activity, why are stains (like safranin) and glycerin used? What would happen if a coverslip traps air bubbles? (3 Marks)

Q11: You observe pond water and soil suspension under a microscope. List two likely microorganisms from each and one short identifying feature. (3 Marks)

Q12: (a) Describe an investigation to show that yeast needs warmth and sugar to make dough rise. 
(b) Explain the role of temperature and sugar in this process. (5 Marks)

Q13: Answer the following based on cells and microbes. 
(a) Why is a cell called the basic unit of life? 
(b) Distinguish bacteria from plant/animal cells in terms of the nucleus. 
(c) Explain how microorganisms both “clean the environment” and “help in food”. (5 Marks)