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Tuesday 18 July 2017

FREE NECO 2017 BIOLOGY OBJ&THEORY ANSWER LOADING!!!

biology Neco answers 

1ai.Homeostasis can be defined as a property of an organism or system that helps it maintain its parameters within a normal range of values
ii. 1.Auxin
2.Ethylene
iii. Euglena as plant
1.It contains chloroplasts in its cytoplasm

2. It is able to produce its own food by photosynthesis when light is available
Euglena as animal:
1. It can actually move as it has a flagellum. Movement is usually associated with animals.
2. It feeds on food whenever it needs to feed by engulfing the food with its body as our phagocytes do when the sunlight is not available.

1aiii)
- Euglena do photosynthesis using the same basic process that plants use. They also move around and eat, as do animals

-Most species of Euglena have photosynthesizing chloroplasts within the body of the cell, which enable them to feed by autotrophy (making energy-containing organic molecules from inorganic raw material through the use of an energy source such as sunlight), like plants. However, they can also take nourishment heterotrophically (making use of food that comes from other organisms in the form of fats, carbohydrates, and proteins), like animals.

2bi)_*Carbon dioxide:* With the increase of CO in air, rate of respiration decreases slightly.

*Temperature:* Below 20 C and above 45 C the rate of respiration reduces. The optimum temperature for respiration is 20 C – 45 C.

2bi)Difference Between Artery and Vein
Artery
1. Vessels which carry blood from the heart to various body parts
2. Arteries carry oxygenated blood from the heart except pulmonary artery
3. Arteries have thick elastic muscular walls
4. Valves are absent
5. Blood flows under high pressure
Vein
1. Vessels which carry blood from the various body parts to the heart
2. Veins carry deoxygenated blood from the various body parts except pulmonary vein
3. Veins have thin non elastic walls
4. Valves are present to prevent the backward flow of blood
5. Blood flows under low pressure

2bii)
-Adenovirus 
-Nephritis
-Alagille 
-Amyloidosis

3ai) Enzyme : Proteins that speeds up the rate of a chemical reaction in a living organism. An enzyme acts as catalyst for specific chemical reactions, converting a specific set of reactants (called substrates) into specific products. Without
enzymes , life as we know it would not exist.

II) cyclosis: the circulation of cytoplasm or cell
organelles, such as food vacuoles in some protozoans

III) peristalsis: the progressive wave of contraction and relaxation of a tubular muscular system, especially the alimentary canal, by which the contents are forced through the system.

3bii) The dental formula for different species are as follows where I = incisors, C = canines, P = 
and M = molars :
Man (adult)
I - 2/2 C - 1/1 P - 2/2 M - 3/3 = 16 x 2 = 32

3cii) Main Functions Of Amniotic Fluid
Provides Mechanical Protection : One of the main functions of amniotic fluid is to prevent mechanical trauma to the fetus. It keeps the growing fetus encased safely, acting as a shock absorber of sorts. Amniotic fluid provides a well-lubricated environment for the fetus to move around in, thereby helping in bone growth and strengthening.

Allows Development of Body Parts: Amniotic fluid circulates freely within the womb, keeping every part of the body lubricated. That allows for the growth of the external body parts such as fingers and toes and stops them from becoming clumped together. It also helps in the development of the lungs and the digestive system.

Offers A Natural Immune System : Amniotic fluid is a significant player in the baby’s natural immune system. Many of the antimicrobial substances that make up the natural immune system of the baby can be found in amniotic fluid. These antimicrobials protect the baby from various bacteria, fungi, protozoa, and viruses

5ai) primary successions :Primary succession is one of two types of biological and ecological succession of plant life, occurring in an environment in which new substrate devoid of vegetation and other organisms usually lacking soil, such as a lava flow or area left from retreated glacier, is deposited.
II) primary roots: The primary root is the central, first-formed, main root . The primary root originates at germination stage from the radicle of the seed. During its growth it branches to form the secondary Roots.
III) macronutrient: any of the nutritional components of the diet that are required in relatively large amounts: protein, carbohydrate, fat, and the macromineral


5bi) Asthma.
Collapse of part or all of the lung (pneumothorax or atelectasis)
Swelling and inflammation in the main passages (bronchial tubes) that carry air to the lungs (bronchitis)
COPD (chronic obstructive pulmonary disease)

II) 1 . Air
Air is a major source of pathogens.For example when a person having common cold snezzes the pathogens enter air and when inhaled they cause common cold to another healthy person.Thus we should ensure good air circulation in our homes ,schools or public places to control pathogens.
2. Water
Water is also a major cause of diseases.Tharefore we should ensure that we schould have clean boiled water or should have aquaguarrd in our homes.
3.Sterlization
It destructs pathogens in medical and lab rooms .We sterlize equipments by heating , freezing or by use of radiation.
4. By use of chemicals
We use chemicals like alcohol to kill pathogens

III) - On the species level, variation allows a population to maintain a healthy diversity, allowing it to cope with changing circumstances.
- Variation within a population is beneficial to the species as a whole due to subtle or dramatic changes in the environment. If changes do occur in the environment, those with variation which favors the new conditions will live to pass on those genes which do well in the new environment.
- It helps in maintaining life even in adverse conditions, as some individuals having variation can even survive in adverse environment. So, natural selection will result in survival of the species having variation which makes it better than others.
5c) Plants reproduce using eggs and sperm, just like people. However, they don't have physical sex! Male plants release pollen , which fertilize
ovaries . The fertilized ovaries develop into
seeds , which can then be distributed to make new plants. As the fertilized ovaries develop, a surplus of carbohydrates and proteins are stored inside the seed. This will serve as food for the plant until it can develop leaves. Next, the fertilized plant ovaries develop the hardened coat we see as the outside of seeds to protect them against harsh environmental conditions. The seeds then can be carried away by wind or animals to create new plants.
The hard outer covering of seeds protects them until germination
*Seed Germination*
After the seed has made it to a new location and is covered with dirt, it can begin germination. Germination is the process of seeds developing into new plants. First, environmental conditions must trigger the seed to grow. Usually, this is determined by how deep the seed is planted, water availability, and temperature. When water is plentiful, the seed fills with water in a process called imbibition . The water activates special proteins, called
enzymes , that begin the process of seed growth. First the seed grows a root to access water underground. Next, the shoots , or growth above ground, begin to appear. The seed sends a shoot towards the surface, where it will grow
leaves to harvest energy from the sun. The leaves continue to grow towards the light source in a process called
photomorphogenesis

Typing..........

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