Biology Questions and Answers - Form 1 Mid Term 2 Exams 2023

Instructions

• (Answer all the questions)

QUESTIONS

1. Define the following terms:   (5 marks)
   1. Organelle
   2. Cell
   3. Tissue
   4. Organ
   5. Organ system
2. State the functions of each of each of the following cell organelles. (5 marks)
   1. Mitochondrion
   2. Lysosomes
   3. Ribosomes
   4. Nucleus
   5. Chloroplasts
3.              
   1. What do you understand by the term cell specialization? (2 marks)
   2. Explain how the following cells are specialized to perform their functions
      1. Sperm cell    (2 marks)
      2. Root hair cell      (1 mark)
4. A student used a light microscope to observe a specimen. He observed eight cells along the diameter of field of view of length 20mm. Find the size of one cell in micrometres. (3 marks)
5. State five differences between a plant cell and an animal cell.   (5 marks)
   

   Plant cell	Animal cell

6. If the eye piece magnification is ×10 and the objective lens has a magnification of ×15. Find the total magnification.   (3 marks)
7. State five differences between a light microscope and an electron microscope. (5 marks)
   

   Light microscope	Electron microscope

8.                                 
   1. Draw a well labelled diagram of a hand lens.   (3 marks)
   2. A student used a hand lens to magnify an insect. The actual length of the insect was 2.5cm. The length of the drawing was 7.5cm. Determine the magnification.  (3 marks)
9.                        
   1. What is cell physiology?             (1 mark)
   2. State the three physiological processes. (3 marks)
   3. State three factors that affect diffusion process.  (3 marks)
   4. Distinguish between osmosis and diffusion.  (2 marks)
   5. State three roles of diffusion in living organisms. (3 marks)
10. Explain the term semi-permeability as a property of a cell membrane.(1 mark)

MARKING SCHEME

1. Define the following terms:   (5 marks)
   1. Organelle
      • a structure within a cell
   2. Cell
      • basic functional unit of a living organism
   3. Tissue
      • a group of cells specialized to perform a specific function
   4. Organ
      • a group iof tissues specialised to perform a specific function
   5. Organ system
      • a group of organs specialised to perform a specific function
2. State the functions of each of each of the following cell organelles. (5 marks)
   1. Mitochondrion
      • site for respiration that provides energy for the cell
   2. Lysosomes
      • contain lytic enzyme which destroys worn out organelles and worn out cells
   3. Ribosomes
      • protein synthesis
   4. Nucleus
      • controls the activities of the cell
   5. Chloroplasts
      • site for photosynthesis
3.              
   1. What do you understand by the term cell specialization? (2 marks)
      • structural modification of a cell to perform a specific function
   2. Explain how the following cells are specialized to perform their functions
      1. Sperm cell    (2 marks)
         • has a tail to propel it towards the ovum
         • has many mitochondria to provide energy
      2. Root hair cell      (1 mark)
         • has an  extended surface for absorbtion of water and mineral salts
4. A student used a light microscope to observe a specimen. He observed eight cells along the diameter of field of view of length 20mm. Find the size of one cell in micrometres. (3 marks)
   • size of cell = diameter of field of view
                                   no of cells
     20 x 100
          8
     = 2500 mm
5. State five differences between a plant cell and an animal cell.   (5 marks)
   

   Plant cell	Animal cell
   has cell wall	lack of cell wall
   has chloroplasts	lack of chloroplast
   regular in shape	irregular in shape
   has no centriole	has centriole
   usually larger	often small

6. If the eye piece magnification is ×10 and the objective lens has a magnification of ×15. Find the total magnification.   (3 marks)
   • total mag = ey2 piece lens magnification x objective lens mag
     10 x 15 = x150
7. State five differences between a light microscope and an electron microscope. (5 marks)
   

   Light microscope	Electron microscope
   uses light to illuminate the specimen	uses a beam of electrons to illuminate the specimen
   has low resolving power	has very high resolving power
   has low magnification power	has very high magnification power
   uses glass lenses for magnification	uses electromagnetic lenses for magnification
   specimen are stained using normal dyes	specimen are strained using complex stains

8.                                 
   1. Draw a well labelled diagram of a hand lens.   (3 marks)
      
   2. A student used a hand lens to magnify an insect. The actual length of the insect was 2.5cm. The length of the drawing was 7.5cm. Determine the magnification.  (3 marks)
      • magnification = drawing length/actual length
        = 7.5/2.5
        = 3
9.                        
   1. What is cell physiology?             (1 mark)
      • study of cell function
   2. State the three physiological processes. (3 marks)
      • diffusion 
      • osmosis
      • active transport
   3. State three factors that affect diffusion process.  (3 marks)
      • temperature
      • type of medium
      • surface area
      • size of molecule
   4. Distinguish between osmosis and diffusion.  (2 marks)
      • osmosis - the movement of water molecule from a region of high concentration to a region of hich concentration to a region of low concentration through a semi - permiable membrane
      • diffusion - movement of molecules from an area of high conc to an area of low conc
   5. State three roles of diffusion in living organisms. (3 marks)
      • absorption of mineral salts
      • absorption of digested food
      • gaseous exchange
10. Explain the term semi-permeability as a property of a cell membrane.(1 mark)
    • selective movement of materials in and out of the cell