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Hello Assignment




LEVEL: 100





  1. Structure and functions of the following:

a)    Nucleus:

Structure: consists of nuclear envelope, a double membrane that encloses the entire organelle and isolates its contents from the cellular cytoplasm. It appears as a dense, roughly spherical or irregular shaped organelle.

Function: provides site for genetic transcription. Controls gene expression and mediate the replication of DNA during cell cycle.

b)     Golgi Apparatus

Structure: It is a membrane organelle which is sac-like. It is found in the cytoplasm of either a plant or an animal cell. The membrane bound structure is called Cisternae.

Function: It modifies, sorts and packages the macromolecules that are synthesized by the cells for secretion purposes or for use within the cell. Creates lysosomes. It transports lipid molecules around the cell. It involves sulfation process of certain molecules. It is a site for the synthesis of carbohydrates.


c)      Vacuoles

Structure: It is a membrane bound organelle with little or no internal structure but they serve several functions.

Functions: Plant cells use there vacuoles for: transport and storing nutrients, metabolites and waste products.


d)     Endoplasmic Reticulum

Structure :It is a extensive membrane network of cisternae (sac-like structures), which are held together by the cytoskeleton.


Functions : provides increased surface area for cellular reactions. Helps in the formation of nuclear membrane during cell division.  They play a very vital role in the synthesis of protein, lipids, glycogen and other steriods like cholesterol, progesterone, testosterone, etc. Transports proteins and other carbohydrates to another organelle, which includes lysosomes, golgi apparatus, etc


e)    Mitochondria

Structure : Mitochondria are rod shaped found in both plant and animal cells. It is a double membrane bound organelle. It has the outer membrane and inner membrane. The membranes are made up of phospholipids and proteins.


Function:They act as the powerhousesof the cells. They are organelles that act like a digestive system which takes in nutrients, breaks them down and creates energy rich molecules for the cell. Respiration takes place here, where glucose and oxygen are changed into energy.

f)      Plasma Membrane also called Cell Membrane

Structure :consist of a lipid bilayer with embedded proteins.

Function:protects the cell by allowing only selected substances into the cell. Serves as a base of attachment for cytoskeleton in some organisms and the cell wall in others. Supports the cell and helps it maintain its shape.


g)    Chromosomes

Structure:a thread like structure found in the nuclei of both plant and animal cells.  Made up of protein and one molecule of DNA (deoxyribonucleic acid)

Function: the structure of the chromosomes help ensure the DNA remains tightly wrapped around the proteins; otherwise DNA molecules would be too large for the inside of the cells.


h)    Microbodiesorganelles in a microbody are peroxisome, glyoxysomes, glycosomes and hydrogenosomes.

Structure:is a vesicle with spherical shape, ranging from 0.2-1.5 micrometers in diameter. Found in the cytoplasm of a cellbut is only visible with the aid of a microscope.

Functions:contains enzymes that participate in the preparatory or intermediate stages of biochemical reactions within the cell. This facilitates the breakdown of fats, alcohols and amino acids. They are involved in detoxification of peroxides and in photorespiration in plants.

i)       Ribosomes

Structure:composed of protein and RNA

Function: cell structures that synthesizes protein which repairs damages or directing chemical processes. Which is very essential and important for the survival of living things.



  1. Eukaryotic cells
  2. Rotational, like a motor, very fast moving.
  3. Nexin arm present
  4. Cilia are short, hair like appendages extending from the surface of a living cell.


  1. Both eukaryotic and prokaryotic cells.
  2. Wave-like, undulating, sinusoidal, slow movement compared to cilia.
  3. Nexin arm absent
  4. Flagella are long, thread-like appendages on the surface of a living cell.



Number 2









Number 3

       Ultra-structure of plant and animal cells.


Number 4

Eukaryotic Cell

Prokaryotic Cell



  • Nucleus is present


  • Nucleus is absent
  • Presence of membrane bound organelle
  • Mitotic division occurs.
  • No membrane bound organelle.
  • Mitotic division doesn’t occur.
  • Usually multicellular
  • Usually unicellular
  • Endoplasmic reticulum and mitochondria present
  • Endoplasmic reticulum and mitochondria absent.
  • Larger ribosomes
  • Smaller ribosomes.



Number 5

Symbiosis also called Mutualism is a type of positive type of ecological interaction. It is a symbiotic association between two organisms in which both the interacting partners are mutually benefited.+/+ is used to represent the interaction meaning both organisms benefit from the association. Examples pollination by animals, lichens, symbiotic nitrogen fixation: rhizobium and leguminous, mutual defense in ants and acacia.

Number 6

Parasitism is a negative ecological interation between two organism in which one organism gains and the other doesn’t but instead looses. Prasitism is represented by +/-. Parwsites that live outside the body of their host are called Ectoparasiteswhile the parasites that live within the body of their hosts are called Endoparasites. Parasites gain from their host while either harming them by damaging their tissues or by producing toxic substances in the body of their host.  Example of parasites includes fungi, protozoan, tick bedbug, lice, flea, etc.  Examples of parasitic organization are cuscuta, loranthus and viscum (loranthaceae), mistletoe,  etc.


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