Category: Bio Questions and answers
State the functions of human gonads.
The two major functions of the gonads in the adult are steroid hormone production and gametogenesis The ovaries produce (eggs/ova) and secrete estrogen and progesterone. These hormones ... Read More
Describe ecological effects of drainage of nitrate fertilizers into rivers and streams.
Accumulation of nitrates in the streams (eutrophication) encourages proliferation of protists and algae on the surface of water. When the algae die, bacterial decomposers use ... Read More
Give three ways in which plants use the nitrates they have absorbed.
Synthesis of chlorophyll Synthesis of enzymes, and hormones Synthesis of nucleic acids They are determinant of osmotic pressure of the cell sap They are determinant ... Read More
Describe how plants absorb nitrate from the soil.
Plants absorb nitrates through root hairs using passive and active mechanism. The nitrates cross the cortex of the root through the apoplast, symplast and vacuolar ... Read More
Advantages and disadvantages of vegetative propagation
Involve use of plant materials other than seeds such as cutting (sweet potatoes, cassava) suckers (pineapple, banana), stem tubers (iris) Advantages Take short time ... Read More
Describe how new species of organism may arise
The process by which new species arise in known as speciation. Speciation to occur their must genetic isolation of a pollution for enough time to ... Read More
Describe how new species of organism may arise
The process by which new species arise in known as speciation. Speciation to occur their must genetic isolation of a pollution for enough time to ... Read More
Describe what would happen in an individual who develops a malfunctioning liver.
Solution The liver is the largest organ and center of metabolic activity in the body. Its failure to function properly it fails the following ... Read More
Explain the following observations in human; production of large volumes of dilute urine on cold day; urine production almost stops as a result of serious blood loss; presence of sugar in urine; feeling hungry faster in cold weather
Production of large volumes of dilute urine on cold day On cold day little or no sweating occurs, loss of water through the skin is ... Read More
Describe how vascular cambium bring about growth in higher plants
This is located between xylem and phloem and its activity causes secondary growth or increase in girth. The vascular cambium consists of two types of ... Read More
Describe how apical meristem bring about growth in higher plants
The apical meristem consists of the tunica and corpus The cells of the tunica region divide repeatedly by mitosis, perpendicular to the surface. This results ... Read More
How does growth in mammals differ from that in flowering plants?
Growth in mammals Growth in plants Growth occurs in all body parts Growth is limited to particular parts called meristem Growth is limited for some ... Read More
State three ways in which water has similar functions in both plants and animals.
water is a reactant in metabolic reactions Water is solvent Water provides support in plants and animals Evaporation of water from plants and animals causes ... Read More
Behavioural means of minimizing water loss in plants
Behavioural means of minimizing water loss in plants some plants shade off their leaves during water shortage to reduce surface area for transpiration. Some plants ... Read More
Physiological means of minimizing water loss in plants
Some rise the osmotic pressure of their roots e.g. taking up salts from the soil actively to increase the rate of water uptake to replace ... Read More
State assumptions, and two precautions, which are taken into account while using this capture recapture method in estimating population size
Assumptions The organisms are randomly distributed The organisms do not show sudden changes in population size due to migration, immigration or emigration Negligible predation Marks ... Read More
UACE BIOLOGY PAPER 2 2000 marking guide
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UACE BIOLOGY PAPER 1 2000 marking guide
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UACE BIOLOGY PAPER 2 2001 marking guide
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UACE Physic paper 1 2019 marking guide(A-level)
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Give three ways in which ions are regulated in the body
Hormone regulate the concentration of ions by (i) controlling uptake of ions from the gut (ii) controlling release of ions from storage organs such as ... Read More
The pH of blood and tissue fluid I human remains constant at about 7.4 in spite of metabolic activities which produce hydrogen ions. Explain how this constancy is maintained by the kidney.
In the cells of proximal convolute tubule, carbon dioxide reacts with water to form carbonic acid. the reaction is catalyzed by carbonic anhydrase enzyme Carbonic ... Read More
UACE BIOLOGY PAPER 1 2001 marking guide(UNEB)
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How vertebrates are adapted to terrestrial life
Their vertebral column and limbs provide support and aid movement They have bones, joints, ligaments and muscles to effect movement They have well developed osmoregulatory ... Read More
Importance of bacteria
Harmful effects Bacteria are agents of disease of animals and plants such as syphilis, cholera, tetanus Bacteria cause milk and food deteriorate Denitrifying bacteria such ... Read More
Nutritional groups of bacteria
Bacteria are heterotrophic or autotrophic There are two main groups of autotrophic bacteria; photosynthetic bacteria and chemosynthetic bacteria Photosynthetic bacteria utilize light energy to build ... Read More
Differences between eukaryotic and prokaryotic cells
Prokaryotic cell Eukaryotic cell 1. DNA not enclosed in membrane DNA enclosed in a double membrane nucleus 2. Has small ribosome (70s) Has ... Read More
How muscle contract
Skeleton muscle contraction is initiated by arrival of a nerve impulse at the nerve muscle junction. Arrival of the nerve impulse cause influx of calcium ... Read More
How a skeletal muscle differs from a smooth muscle
Skeletal muscle Smooth muscle - Cell are multi nucleated Each cell contain a singe nucleus - Many striations of alternating light and dark bands Not ... Read More
Adaptations of plants to capturing maximum light
Cells in upper layer contain numerous chloroplast Leaves provide large surface area to trap light Leaves are arranged in mosaic manner to expose each leaf ... Read More
UACE BIOLOGY PAPER 2 2002 marking guide
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UACE BIOLOGY PAPER 1 2002 marking guide
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What consideration must be made before application of a biological pest control method?
Sc Whether the control egent is specific to intended pest Rate of reproduction of both pest and control organism Control organism should feed on all ... Read More
structural and physiological functions of fats
Structural functionsof fats Make up cell membrane Protection: lipids are constituents of the waxy cuticle of plants and insects Lipids are water repellant thus prevent ... Read More
describe structural and biochemical adaptations of red blood cells
Structural adaptation of red blood cells Thin membrane to reduce diffusion distance of gases Biconcave shape increase surface area for gaseous exchange Lack of nucleus ... Read More
Describe the trend of succession that would take place on a bare rock.
Succession on bare rock is called primary succession and occurs in three stages. Pioneer stage Bare rock breaks down physically and chemically during the ... Read More
Outline the flow of energy in the climax community
Energy in form of light from the sun is used for photosynthesis to produce organic molecules. The initial amount of energy fixed by ecosystem ... Read More
Adaptation of amoeba for gaseous exchange
Has large surface area to volume ratio Has thin membrane Read More
Adaptations of flowering plants to gaseous exchange
Has many stomata on leaves and lenticel to allow gaseous exchange Broad leaves gives provide large surface area for gaseous exchange Cells in mesophyll layer ... Read More
Adaptation of an insect for efficient gaseous exchange
Has highly branched tracheal system that ramify the whole body up to individual cells Tubules open to atmosphere to receive oxygen through spiracles Tracheoles have ... Read More
Qualities of gaseous exchange surface
Has large surface area Moist Thin to reduce distance for diffusion Freely permeable to respiratory gases Has good blood supply Has good ventilation Read More
UACE BIOLOGY PAPER 2 2003 marking guide (UNEB)
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UACE BIOLOGY PAPER 1 2003 marking guide (UNEB)
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State the importance of magnesium in plant metabolism.
It is a constituent of chlorophyll It activates enzymes in protein synthesis It is co-factor for many enzymes e.g. ATPase Read More
State the importance of calcium in plant metabolism.
It activates several enzymes e.g. ATPase It is important for translocation of carbohydrate It is a constituent of the plant walls It is important in ... Read More
State on indicator in the environment where there is prevalence of high levels of sulphur dioxide in the atmosphere.
Disappearance of lichen and mosses Discoloration and damage to building, sculptures and fabric Chlorosis and necrosis of vegetation Read More
Describe the how terrestrial plants overcome the challenges of terrestrial environment.
They have shinny leaf surfaces to reflect much of the incident light rays do avoid overheating. They have a thick, waxy cuticle impermeable to water. ... Read More
Discus the factors that affect the rate of diffusion at a respiratory surface.
Surface area of the respiratory surface; the larger the surface area across which diffusion can occur, the higher the diffusion rate. A large surface area ... Read More
How are the conditions for efficient gaseous exchange fulfilled in mammalian lungs?
The lungs have numerous alveoli which represent a highly folded respiratory membrane to provide a large area for diffusion of the gases. Lungs have a ... Read More
The diameter of capillaries is smaller than the diameter of the red blood cells passing through them. How does this relationship help in gaseous exchange in lungs?
The red blood cell membrane is in close association with the capillary membrane all through its passage. This reduces the distance across which gases diffuse ... Read More
What is the effect of inbreeding in a population?
It reduces variations in a population Lethal or useful characteristics are retained in the population Promotes desired characteristics in population Read More
Describe the mechanisms which limit inbreeding in plants.
In some plants, the stigma matures before the anther so that it gets ripe before the anther is able to produce mature pollen grains. Thus ... Read More
UACE BIOLOGY PAPER 2 2005 marking guide (UNEB)
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UACE BIOLOGY PAPER 1 2005 marking guide (UNEB)
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UACE BIOLOGY PAPER 2 2006 marking guide (UNEB)
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Suggest the factors that would cause immigration of new species to a virgin island.
Availability of food on the island. Favorable environmental conditions on the island. Accidental movement of organisms to the island. For example flying and swimming organisms ... Read More
Describe the physiological changes that occur in a seed during germination
Germination starts with the rapid uptake of water by the seed through the micropyle by a process called ambition. Water then moves from cell by ... Read More
Giving reasons, suggest suitable conditions under which seeds for planting should be stored
dry condition; too much water may cause rotting dry seeds; seed with high content promotes diseases optimum temperature; high temperature promotes pests and diseases low ... Read More
Describe the adaptations of blood in terrestrial animals living in the following environmental conditions
Extreme oxygen tensions (08 marks) Extremes of oxygen tension can the very high or very low values of oxygen partial pressure. In all these conditions, ... Read More