Nabteb Expo questions and answer, Nabteb Biology Expo, Nabteb Biology Runs, Nabteb Expo 2023, Biology Answers
Please answer only four questions, at least one (1) from each section.
(Diagram of Euglena)
(i) Euglena can move actively, propelled by its flagellum.
(ii) Euglena can engulf food particles through a process called phagocytosis.
(i) Euglena contains chloroplasts, enabling it to perform photosynthesis.
(ii) Euglena can store excess energy in the form of paramylon granules.
(i) Robert Hook
(ii) Matthias Schleiden
(i) Robert Hooke’s contribution: Hooke’s observation of cells in cork and his subsequent publication of “Micrographia” helped establish the concept of cells as the basic building blocks of living organisms. His work provided early insights into the microscopic world and laid the foundation for the study of cytology.
(ii) Matthias Schleiden’s contribution: Schleiden’s cell theory expanded upon Hooke’s observations. He proposed that not only plant tissues but all organisms are composed of cells. Schleiden’s work emphasized the fundamental role of cells in the structure and function of living organisms, thus contributing significantly to the development of cytology.
(i) epigeal germination
(ii) hypogeal germination.
(i) Epigeal germination is the type of germination where the cotyledons emerge above the soil surface and the shoot system develops first followed by the root system. The cotyledons of such plants become green and photosynthetic and the plant relies on them until it develops true leaves.
(ii) Hypogeal germination is the type of germination where the cotyledons remain underground and the radicle emerges first, followed by the shoot. The cotyledons in such plants are mostly modified to serve as food storage organs, and they do not become photosynthetic.
(i) Epigeal germination: bean (Phaseolus vulgaris)
(ii) Hypogeal germination: maize (Zea mays)
(2bi) Transportation pull in plants refers to the mechanism by which water is pulled up from the roots to the leaves against the force of gravity. This process is primarily driven by transpiration, which is the loss of water vapor from the leaves through stomata. As water evaporates from the leaf surface, it creates a negative pressure or tension in the xylem vessels, resulting in a pull that draws water upward.
(i) Stomata are small pores found on the surface of leaves
(ii) Lenticels are small raised openings found on the bark of woody stems.
Experiment to Determine the Water Content of a Soil Sample:
(ii) Balance (to measure mass)
(iii) Soil sample
(iv) Porcelain crucible or aluminum container
(v) Desiccator (optional)
(vi) Heat-resistant gloves
(i) Preheat the oven to a temperature between 105°C and 110°C (221°F and 230°F).
(ii) Weigh the clean and dry porcelain crucible or aluminum container and record its mass (M1).
(iii) Take a representative soil sample from the desired depth of the soil profile. Ensure the sample is free of large stones, roots, and organic debris.
(iv) Place the soil sample into the crucible or aluminum container and record the combined mass of the soil and container (M2).
(v) Spread the soil sample uniformly across the crucible or container to increase the surface area for better drying.
(vi) Place the crucible or container with the soil sample into the preheated oven and let it dry for approximately 24 hours. This allows the water to evaporate completely from the soil sample.
(vii) After 24 hours, remove the crucible or container from the oven using heat-resistant gloves and place it in a desiccator to cool. Once cooled, measure the mass of the crucible or container with the dried soil (M3).
(viii) Calculate the water content using the formula:
Water Content (%) = ((M2 – M3) / (M2 – M1)) x 100
Note: M1 represents the mass of the empty crucible or container, M2 represents the combined mass of the soil and container before drying, and M3 represents the mass of the dried soil and container.
(i) Loamy soil: Loamy soil has moderate capillarity. It can retain water well, but excess water can still drain away.
(ii) Clay soil: Clay soil has high capillarity. It can hold onto water for extended periods and tends to become waterlogged.
(iii) Sandy soil: Sandy soil has low capillarity. It does not retain water well and allows water to pass through quickly.
(i) Loamy soil: Loamy soil has a balanced porosity, consisting of a mixture of sand, silt, and clay particles. It provides a good balance between drainage and water-holding capacity.
(ii) Clay soil: Clay soil has high porosity due to its fine particles, but it has poor permeability. It can hold onto water tightly but drains poorly.
(iii) Sandy soil: Sandy soil has high porosity due to its coarse particles. It drains well but has a low water-holding capacity.
(i) Mode of Communication
(iii) Duration of Response
(iv) Target Range
(i) Electrical impulses (nerve impulses)
(ii) Rapid response
(iii) Immediate and short-lived
(iv) Localized, specific target areas
(i) Chemical messengers (hormones)
(ii) Slow response
(iii) Delayed and long-lasting
(iv) Widespread, generalized target areas
(i) Control of Growth: Thyroxine promotes the growth of tissues and organs during metamorphosis, leading to the transformation of larvae into adult amphibians.
(ii) Development of the Respiratory System: Thyroxine stimulates the development of lungs and gills in amphibians, facilitating their transition from an aquatic to a terrestrial lifestyle.
(iii) Metabolic Regulation: Thyroxine affects the metabolic rate of amphibians, increasing energy consumption and providing the necessary resources for the transformation process.
(iv) Differentiation of Tissues: Thyroxine influences the differentiation of various tissues, including skin, limbs, and reproductive organs, enabling the distinct morphological changes seen in different stages of metamorphosis.
A sense organ is a specialized part of an organism’s body that detects and responds to external stimuli, allowing the organism to perceive and interact with its environment. Sense organs are responsible for receiving sensory information and transmitting it to the brain for processing.
(i) Eyes: The eyes are responsible for vision, allowing mammals to perceive and interpret light and color.
(ii) Ears: The ears enable mammals to detect and interpret sounds, providing the sense of hearing. They also help with balance and spatial orientation.
(iii) Nose: The nose contains olfactory receptors that allow mammals to detect and interpret different odors, providing the sense of smell.
(iv) Skin: The skin is the largest sense organ in mammals. It contains various receptors that enable the sense of touch, temperature perception, and pain sensation.
(i) Metabolism: The liver plays a crucial role in metabolism by breaking down nutrients, such as carbohydrates, proteins, and fats, and converting them into usable forms for the body.
(ii) Detoxification: The liver helps detoxify harmful substances, such as drugs, alcohol, and metabolic waste products, ensuring their elimination from the body.
(i) Filtration and excretion: The kidneys filter waste products, excess water, and other substances from the bloodstream to produce urine.
(ii) Regulation of blood pressure: The kidneys help regulate blood pressure by controlling the balance of salt, water, and minerals in the body.
A mutation refers to any change or alteration in the DNA sequence of an organism’s genome.
Gene flow refers to the transfer of genetic material (genes) from one population to another through interbreeding or the movement of individuals.
(i) 50% of their offspring are expected to be colour blind
(ii) 50% of the male offspring are expected to be colorblind.
(i) A pyramid of numbers is a graphical representation of the number of individuals at each trophic level in an ecosystem. It illustrates the relative population sizes of different species within a food chain or food web.
(ii) The pyramid of energy represents the flow of energy through different trophic levels in an ecosystem. It illustrates the amount of energy available to each trophic level and the energy transfer from one level to another.