Wednesday, 19th April, 2017
Biology 2 (Essay) 2.00pm – 3.40pm
Biology 1 (Objective) 3.40pm – 4.30pm
1ai) Classifications of living things consists of placing together in categories those living things that resembles each other. It involves placing living things into groups that have certain features in common which distinguish them from other groups
1aii) Car von Linnè Also known as Carolus Linnaeus
1aiii)-Classification is important because it allows scientists to identify the organisms
-Classification is important because it makes it easy for scientists to group the organisms.
– It is also good to properly name organisms via a standardized system
– Phylum(Animal) or division (Plant)
1bi) -Vírus can reproduce when present in another living cell
-It possesses characteristics which can be transmitted from one generation to the next
1bii) -When a virus is extracted from a living cell and placed in a non living medium, it assumes a crystalline form and thus become non-living
-Virus cannot respire, excrete or respond to stimuli
2a)i They catalyse reactions by lowering the activation energy of a reaction
ii). They are regenerated after each reaction
iii). They are substrate specific, hence only molecules which are complementary to their shape can bind to it.
iii). They aid in metabolism (anabolism and catabolism)
2Bi) The Small Intestine
i) 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.
Phosphorus: loss of appetite and changes to weight
Nitrogen: It leads to poor growth of plant.
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.
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…
No color change (Iodine Solution remains brown)
Iodine/Potassium Iodide solution changed from brown to blue- black
Starch is not present
Starch is present
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.
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.
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.
6a) Vaporized odor molecules (chemicals) floating in the air reach the nostrils and dissolve in the mucus (which is on the roof of each nostril). Underneath the mucus, in the olfactory epithelium, specialized receptor cells called olfactory receptor neurons detect the odor. These neurons are capable of detecting thousands of different odors. The olfactory receptor neurons transmit the information to the olfactory bulbs, which are located at the back of the nose. The olfactory bulbs has sensory receptors that are actually part of the brain which send messages directly to: The most primitive brain centers where they influence emotions and memories (limbic system structures), and “Higher” centers where they modify conscious thought (neo-cortex). These brain centers perceive odors and access memories to remind us about people, places, or events associated with these olfactory sensations.
6 b )
ii ) Membranes
iii ) Airspace
6 ci )
autotrophs are organisms that can synthesizes food from inorganic substances by using chemical energy or light
6 cii )
ii ) Unicellular algae
6 d )
i) providing leadership on matters critical to health
ii ) shaping the research agenda and stimulating the generation
iii ) translation and dissemination of valuable knowledge
iv) setting norms and standards
v) promoting and monitoring their implementation
6 e )
i) plants : Water Wisteria and Java Moss.
ii ) Animals : catfish and earthworm
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