Science 2021 Bece Theory Questions and Answers
Science 2021 Bece Theory questions and answers. Theory questions and answers. 2021 Bece Science theory
2. a. I. State what happens when photosynthesis occurs in a leaf or
Ii. What is pollination?
b. Explain briefly why the Mass of lumpy charcoal remains unchanged when ground into powder but the mass of the same lump changes when heated to burn
c. (I) what is a physical quality?
(Ii) state two physical quantities
d. State two important each of:
(I) light;
(Ii) temperature;
In crop production
Solution to question 2
Science 2021 Bece Theory Questions and Answers
I. What happens when photosynthesis occurs.
– after photosynthesis, glucose and oxygen will be produced. Oxygen serves as the by- product while the main product is glucose. This glucose in the form of energy is used by the leaves and the entire plant for carrying out all the seven life processes.
II. Pollination- it is the transfer of a matured pollen grains from the anther to the stigma of a matured flower.
b. Why mass of grounded charcoal is unchanged but a burnt charcoal changes in masss.
– grounded charcoal is a physical change since there is no new substance formed and the constituents are the same. Besides, it is not accompanied by great heat change hence the mass will remain the same. But as for a burnt charcoal, a new substance is formed called ash hence it is a chemical change. The constituents of the charcoal differs significantly from the ash formed because there is an application of heat which will change the mass.
C.I. Physical quantity is a quantity that can be measured.
II. Two physical quantities
– mass ( base quantity)
– velocity ( derived quantity)
d. Importance of light in crop production
– crops absorb sunlight for photosynthesis
– light is used by seeds for germination
– sunlight helps in seeds and fruits dispersal ( explosive mechanism or self dispersal)
– it helps to dry our crops after harvest.
Importance of temperature in crop top
– low temperature may lead to rain formation which would be absorbed by plants for growth and development
– high temperature will increase plants resistance to pests and diseases and avoid flooding.
– it can influence pollination and fertilization.
– ensures seeds and fruits dispersal
– Can break down the spread of pests and diseases.
– low temperature can reduce humidity and the rate of transpiration in plants
Science 2021 Bece Theory Questions and Answers
3. a. I. What is hardness of water?
Ii. Give one example each of a natural source of water that is:
(a) hard
(b) soft
b. What is the end product of the digestion of each of the following food substances?
I. Meat
Ii. Cassava
III. Palm oil
c. Give one effect of each of the following factors considered in vegetables crop production:
I. Soil type
Ii. Nearness to source of water
III. Nearness to market
d. I. Explain briefly why an eclipse occurs
Ii. Name the two types of eclipse
Bece 2021 science past questions and answers
Science 2021 Bece Theory Questions and Answers
Solution to question 3
a)I. Hardness of water is the inability of water to lather easily with soap. This occurs as a result of the presence of magnesium ions (Mg²+), Calcium ions ( Ca²+) and iron III ions (Fe²+)
II. Sources of:
a. Hard water: lake, sea etc
b. Soft water: bore hole, well, rain water
b) the end product of the digestion of
I- meat_Amino acid
II- cassava– glucose
III- palm oil– fatty acid or glycerol
c. Effects of the following in crop production.
I. Soil type- the type of soil you select determines the fertility rate of that soil. Fertile soil is very productive hence ensures proper growth and development of crops. A less fertile soil will give you a poor yield of crops due to its inability to support proper growth and development of crops.
ii. nearness to a source of water.
The closer the farm is to a source of water, the easier irrigation can be carried out. When the farm is far away from water source, it becomes difficult to apply irrigation.
III. Nearness to the market
It is very easy to convey crops to the market if the farm land is closer to the market. Similarly, crops can easily rot in a case where the farm land is far away from the market. Transportation of crops to the market will become a problem.
d. I. Eclipse is the total or partial disappearance of the sun or the moon which occurs due to the movement of the moon or the earth. This happens when the moon comes between the sun and the earth ( eclipse of the moon) or when the earth comes between the sun and the moon ( eclipse of the sun).
II. Types of eclipse
– eclipse of the sun (solar eclipse)
– eclipse of the moon ( lunar eclipse)
Science 2021 Bece Theory Questions and Answers
4.a. i. Explain the term convection of heat
Ii. Give two reasons why convection does not occur in solids
b. Give two effect of each of the following soil physical properties on maize cultivation
I. Texture
Ii. Water holding capacity
c. Use any Three of the following organisms to construct food chain
Hawk, grasshopper, man, grass, toad and grass cutter.
d. I. Consider the following elements and state which of them are metals
11Na, 7N, 6C, 3Li
Ii. Explain briefly what is observed when pieces of each of the following of metals are dropped into two separate test tubes each containing dilute hydrochloric acid
(a) magnesium
(b) silver
Solution to question 4
Science 2021 Bece Theory Questions and Answers
ai. Convection of heat is the transfer of heat through liquid medium or in fluids eg. Boiling water.
Ii. Why convection does not occur in solids:
– solid particles are too compacted or are closely packed.
– solid has very low kinetic energy between its molecules
– there is strong cohesive force between solid particles or molecules
b. Effects of the following in maize cultivation:
I. Soil texture
– soil which is too smooth or sticky like clay contains Less soil nutrients and also less soil living organisms. This leads to poor yield.
– Soil like loam or sandy- loam with less smoothness in texture will promote good yield of maize.
II. Water holding capacity
– soil with moderate water holding capacity is good for maize cultivation.
– soil with high water holding capacity easily becomes water logged which does not support maize yield.
c. Food chain
Grass_ grasshopper_ toad.
Or
Grass_ grass cutter_ man
d.i. metals
– 11Na
_ 3Li
II. The following metals in hydrochloric acid
a. Magnesium
Magnesium in dilute hydrochloric acid will undergo through chemical reaction to produce salt ( magnesium chloride) and hydrogen gas. (Mg + 2Hcl~Mgcl² + H² )
b. Silver in hydrochloric acid will not form any substance because, silver is a non-metal.
Science 2021 Bece Theory Questions and Answers
5. a. State two important components each of the soil that helps:
I. Crops to grow
Ii. To maintain good soil structure
b. I. Explain how energy in a windmill is obtained.
Ii. State one source of renewable energy
c.i. Explain why steel is preferred to iron in building construction
Ii. State two ways of preventing rusting
d. State three ways of preventing indigestion
Solution to question 5
Science 2021 Bece Theory Questions and Answers
a. Components that help.
I. Crops to grow
– organic matter
– soil living organisms
– soil air
– soil water
Ii. To maintain good soil structure
– organic matter
– soil living organisms
– soil water.
– soil air
b. I. How energy in windmill is obtained.
When wind blows, it turns the blades of the windmill turbines around a motor, which spins a generator, which creates electricity.
II. One source of renewable energy
– wind
– sun
– water
c.i. why steel is preferred to iron in building and construction
– steel is less expensive
– steel does not rust but iron does
– steel is durable than iron
– steel can maintain its properties for long than iron
II. Ways of preventing rusting
– alloying
– galvanizing
– oiling
– painting
d. Ways of preventing indigestion
– eating enough fruit and vegetables
– drink enough water
– exercise regularly
6. a. State Three ways by which the atmosphere in an industrial area is polluted
b. I. Write word equation for each of the following reactions:
(a) calcium and oxygen
(b) nitrogen and hydrogen
Ii. State the hazard that could be prevented through the use of;
(a) Gas mask
(b) googgle
C. If a cuboid of weight 100N, has sides 5 cm by 10 cm, calculate the:
I. Area of the cuboid
Ii. Pressure exerted by the cuboid when it lies on its side
d. I. Explain the term mixed farming
Ii. State two advantages of mixed farming
Science 2021 Bece Theory Questions and Answers
Solution to question 6
a. Ways the atmosphere of industrial area is polluted.
– fumes from cars.
– noise from machine
– smoke from machinery
b.i. word equation for the reaction between:
a. Calcium and oxygen
Calcium+ Oxygen~ Calcium oxide
b. Nitrogen and hydrogen
Nitrogen + hydrogen~ Ammonia gas
Ii. Hazard that could be prevented through:
a. Gas mask.
Protection against inhaling of toxic chemicals or substances
b. Googgle.
Protection against Sparks of fire
C.i area of cuboid
= L× B.
= 5cm ×10cm= 50cm²
II. Pressure= force/Area.
= 100N/50cm²
= 2pa or 2N/cm²
d. I. Mixed farming is the method of farming where a farmer grows two or more different types of crops on the same piece of land.
Ii. Advantages of mixed farming.
– the farmer gets balance diet from the farm
– plants materials can be used to feed animals
– animal droppings can be applied to the crops as organic fertilizer.
Science 2021 Bece Theory Questions and Answers
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