THE CELL

Q1. Describe the structure and functions of various organelles in a mature animal cell(20mks)

Mitochondria

Has a double membrane the outer and the inner surrounding it; the inner folded to form cristae which increase surface area for attachment of respiratory enzymes

Golgi apparatus

These are stacks of membrane-bound sac-like structures that transport glycoproteins, they also pack glycoproteins

Lysosome

Are spherical shaped organelles bounded by a single membrane they contain lytic enzymes which destroy old worn-out organelles

Endoplasmic reticulum

Are membranes bond cavities in the cytoplasm

Smooth endoplasmic reticulum that transport lipids and steroids

Rough endoplasmic reticulum has ribosomes on its surface and transport proteins

Centrioles

Rod shape located outside the nuclear membrane; for the formation of cilia and flagella

Cytoplasm

It is a fluid medium where chemical reactions occur; contains organelles and inclusion

Granules; cell membranes

The cell membrane encloses all cell organelles; has a phospholipid layer between two protein layers, with pores that selectively allows substances to pass in and out/semi-permeable

Nucleus;

Has double membrane around it; with pores allow substances in and out

Ribosome

Are spherical in shape and suspended in the cytoplasm and attached to the endoplasmic reticulum; synthesis proteins

Q2. State Characteristics of living things?

 Nutrition                         

• The process by which organisms obtain food and utilize nutrients  
• Organisms acquire nutrients (food) for various life process like growth

Gaseous exchange      

• The process by which living things take in oxygen and give  out carbon (IV) oxide  
•  Oxygen taken in is for respiration

Respiration                        

• The process by which food materials are broken down chemically to produce energy      
•  Energy is used in various activities like growth

Growth and development      

• Growth is the permanent increase in size
• development is a change in the complexity of structure 
• Enables organism to acquire normal body size essentially for body function

Excretion                          

• The process by which waste materials are eliminated          
• Enables organisms to eliminate waste materials that are toxic if accumulated

Movement/locomotion       -

• A change in whole organism or one part of the body    
• Enables organisms to acquire food, water and mates

Irritability                        

• The ability of organisms to perceive the change in their surrounding     
• Enables organisms to respond to changes

Reproduction                    

• The process by which organisms give rise to young ones     
• It prevents the extinction of organisms

Q3. KCSE Biology The Cell

1. Name the function of the following organelles found in a cell. (2 mark)

      a)    Centrioles 

       b)    Nucleolus 

2. The following diagram shows a specialized cell.

         (a) identify the specialized cell.     (1 mark)

         (b) State the function of the cell named in (a) above.  (1 mark)

3. The diagram below shows a certain cell. Use it to answer questions that follow.

(a )Identify structures labelled A, B, C, and D.      (4 marks)  

(b )Measure the length of the distance between X and Y. If the magnification of the cell is X 10,000. 

(c) Calculate the actual diameter of the cell between points X and Y in micrometres. Show your work. (2 marks)

(d) With reason identify the kingdom from which the cell was obtained. (2marks)

4. What is the importance of fixation in the preparation of temporary slides?                                (1mk)

5. Why are the following steps taken when preparing a crosssection of a leaf for viewing under the microscope?

(a) Cutting thin section.                                                                                     (2 marks)

(b) Placing the section in water.                                                                         (2 marks)

6. State the functions of the following; i) Lysosomes ii) Ribosomes iii) Mitochondrion      (3marks) 

7. A student was using a microscope whose eyepiece lens was marked X4. The high powered objective lenses were marked  X10. Calculate the total magnification of the microscope          (2marks)

8. The diagram below represents microvilli on epithelial cells

1. Name the parts A and C                                                                                   (2marks)

Name two parts in the human body where the above epithelial cells are found.    (2marks)

(a) Name the parts A and C      

(b) Name two parts in the human body where the above epithelial cells are found.    (2marks)                                             

9. Distinguish between resolving power and magnifying power of a microscope        (2 Marks)

10. Name the cell organelles responsible for:

(a) Protein synthesis.                      (1mk)

(b) Destroying worn-out organelles.         (1mk)

11. (a)   Lokori school Biology students used a microscope with x40 objective lens and x5 eyepiece lens which had a 2mm radius. Calculate the area of the field of view in micrometres.       (2mks)

(b)  What is the average size of the cell in micrometres?       (2mks)

12.  State three differences between plant cell and animal cell    (3marks)

13. State one function of revolving nose piece in the light microscope     (1mk)