2017/2018 WAEC BIOLOGY THEORY AND OBJECTIVES ANSWERS EXPO RUNS

2017/2018 WAEC BIOLOGY THEORY AND OBJECTIVES ANSWERS EXPO RUNS

1ai) Classification of living things consists of placing together in categories those living things that resemble each other . It involves placing living things into groups that have certain features in common which distinguish them from other groups
1ai) Carolus Linnaeus
1aiv) Kingdom
           |
Phylum(Animal or Plant)
    |
Class
    |
Order
    |
Family
   |
Genus
    |
Species


2D) Procedures

Remove a green leaf from a plant that has been exposed to sunlight for a few hours
Half-fill a 250cm3 beaker with water. Heat the water until it boils. Keep the water at boiling point.
Use the forceps to place the leaf in the boiling water. Boil for 2 minutes.
Turn off the Bunsen Burner. (If you are using a heat source without a naked flame - electric water bath or hot plate - this step is unnecessary.)
Place the boiled leaf in a boiling tube containing 90% ethanol.
Place the boiling tube in hot water and boil for 10 minutes or until the leaf decolourizes.    ( It may be necessary to replace the ethanol)
Gently remove the leaf and wash with a fine trickle of cold tap water.
Spread the leaf evenly on a white tile.
Add a few drops of iodine/potassium iodide solution to the leaf and note any observations.
Observations/Results
The leaf was flaccid (soft) after being boiled in water
The ethanol changed from colorless to green
The leaf was brittle after being boiled in ethanol
The leaf become flaccid once more after being rinsed in cold water
After iodine solution was added...

OBSERVATIONS                              

No color change (Iodine Solution remains brown)

Iodine/Potassium Iodide solution changed from brown to blue- black

INTERPRETATION


Starch is not present

Starch is present


3C)

Commensalism
Parasitism
Mutualism

3 i)

Commensalism is a type of relationship where one of the organisms benefits greatly from the symbiosis. The other is not helped but is not harmed or damaged from the relationship. In other words, this is a one-sided symbiotic relationship.


3 ii)
In parasitism, one organism benefits from the relationship but at the expense of the other. The organism may live inside the other’s body or on its surface.

In some of these parasitic relationships the host dies and in others, it is important that the host remain alive.

3 iii)

Parasitism

In parasitism, one organism benefits from the relationship but at the expense of the other.

The organism may live inside the other’s body or on its surface. In some of these parasitic relationships the host dies and in others, it is important that the host remain alive.

2c)
Chlorophyll is important to plants because it is the substance that the chloroplast organelles in the cells that carry out photosynthesis - needed by plants as it converts water + carbon dioxide (molecules split by UV light) to glucose (food store for plants) and oxygen.