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2017 WAEC GCE BIOLOGY OBJ AND THEORY ANSWERS

BIOLOGY THEORY ANSWERS BY MR.CODED:-
1a) i).white blood cells
lipids

aii)
i.responsible for the removal of interstitial fluid from tissues

ii.It transports white blood cells to and from the lymph nodes into the bones

1b)
i).oxygen
ii.excretory products, such as carbon dioxide, urea, etc
iii.Hormones

ii)Plants absorb water from the soil through their root hairs which are surrounded by soil water in the soil. The soil water is a more dilute solution than the soil sap inside the root hair hence water molecules move from soil water into the root hairs by the process of osmosis. Mineral salts are absorbed through the cell membrane often from a zone of their low concentration in the soil to a zone of their higher concentration in the cells of the roots through active absorption.

1c)
i).Placentation is the arrangement of ovules within an ovary. The part of the ovary where the ovules are attached is called a PLACENTA.

ii).
Marginal placentation
Parietal placentation
Axile placentation
Free central placentation

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3a)
i.Occurring group of different organisms living together and interacting in the same environment.

ii.Population=is defined as the total number of organisms of the same species living together in a given area
iii.Ecologicalnide==Refers to the specific portion of a habit which is occupied by a particular organism

3b)
Because all living organism need energy and nutrient in an environment in other to sustrundipe

3ci)
1). Lack of enough food
2) out break of disease
3) lack of money

Cii)
i.Exposed the soil into erosion

ii.Cause loss of nutrient into the plant

iii.Cause low yield

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4ai)
Sickle cell anaemia; this is a group of disorders that affects hemoglobin , the molecule in red blood cells that delivers oxygen to cells throughout the body.

4d)
i)The presence of fossils;
preserved impressions of organisms/ ancestors that lived in the past

ii)The vestigial structures;
an organ that serves no purpose anymore but did with a common ancestor

iii)The presence of homologous structures;how the bones or parts of an animal are the same but in different proportions

iv)The comparative embryology; in development, embryos look similar until they differentiate later on

V)The molecular evidence ;comparing DNA; to trace differences and similarities in DNA and other molecules, making the species more or less related.

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5a) A flower formula is a short-hand method for describing a flower using letters,
numbers and symbols to represent the flower parts. There is no single,
standard notation, but they can be useful in visualizing the parts of a flower.

5d) Proteins are long chains of amino acids that form the basis of all life. They are like machines that make all living things, whether viruses, bacteria, butterflies, jellyfish, plants, or human function.

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6bi)

Irritability is the ability to be excited to a characteristic action or function by the application of some stimulus

Or

Irritability is the Abnormal sensitivity or excessive responsiveness, as of an organ or body part, to a stimulus.

6ci) Tillage is the agricultural preparation of soil by mechanical agitation of various types, such as digging, stirring, and overturning. Examples of human-powered tilling methods using hand tools include shovelling, picking, mattock work, hoeing, and raking

6ei) Oviparity is the expulsion of undeveloped eggs rather than live young. The eggs may have been fertilized before release, as in birds and some reptiles, or are to be fertilized externally, as in amphibians and many lower forms. In general, the number of eggs produced by oviparous species greatly exceeds the number of offspring from species that bear live young, but the chances of survival are diminished because of the lack of maternal protection.

Or

Oviparity is the producing eggs that mature and hatch after being expelled from the body, as birds, most reptiles and fishes, and the monotremes.

ii) Viviparity is the retention and growth of the fertilized egg within the maternal body until the young animal, as a larva or newborn, is capable of independent existence. The growing embryo derives continuous nourishment from the mother, usually through a placenta or similar structure.

6f)

Rhizobium turns the free Nitrogen in air into

– Ammonia
– Nitrate

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Posted by on September 9, 2017.

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