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BIOLOGY OBJECTIVE
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NECO 2023 GCE BIOLOGY ESSAY
NUMBER ONE
(1ai)
Organic evolution refers to the gradual change in the genetic makeup of a population over generations, resulting in the development of new species from pre-existing ones. It involves the processes of natural selection and genetic variation.
(1aii)
(i) Animals
(ii) wind
(1aiii)
(i) Photosynthesis is a process in which plants convert carbon dioxide and water into glucose and oxygen, using light energy. *While* Respiration is a process in which cells break down glucose to produce energy, releasing carbon dioxide and water as byproducts.
(ii) Photosynthesis occurs in the chloroplasts of plant cells, *while* respiration occurs in the mitochondria of both plant and animal cells.
(1aiv)
(PICK ANY TWO)
(i) Cell elongation: Auxin promotes elongation of plant cells, leading to growth and development.
(ii) Apical dominance: Auxin inhibits the growth of lateral buds, directing the plant’s growth towards the main apical bud.
(iii) Tropisms: Auxin plays a role in tropisms, such as phototropism (growth towards light) and gravitropism (response to gravity).
(iv) Root formation: Auxin stimulates the formation of roots in cuttings, aiding in vegetative propagation.
(1bi)
Metamorphosis in houseflies (Musca domestica) involves distinct stages of development. It starts with an egg, which hatches into a larva or maggot. The larva goes through several instars, growing in size and molting its exoskeleton. After the larval stage, it enters the pupal stage, during which it undergoes internal changes and transforms into an adult housefly. The adult housefly emerges from the pupa, ready for reproduction.
(1bii)
(i) Subatomic particles: These are the smallest units of matter, such as protons, neutrons, and electrons.
(ii) Atoms: Atoms are the building blocks of matter and comprise subatomic particles. They combine to form molecules.
(iii) Molecules: Molecules are formed by the combination of atoms. They can be simple, like water (H2O), or complex, like DNA.
(iv) Cells: Cells are the basic units of life. They are made up of molecules and carry out various functions necessary for life.
(v) Tissues: Tissues are groups of cells that work together to perform a specific function. They can be found in organs and organ systems.
NUMBER TWO
(2ai)
(i) Imbibition: The seed absorbs water from the soil, causing it to swell and activate biochemical processes within the seed.
(ii) Activation of Enzymes: The imbibed water activates enzymes within the seed, which initiate the metabolic processes necessary for germination.
(iii) Mobilization of Stored Energy: The stored energy reserves, such as starch and proteins, within the seed are broken down into simple sugars to provide energy for the growing embryo.
(iv) Growth of the Embryo: The embryo grows, and the radicle (primary root) emerges from the seed, followed by the emergence of the shoot, which develops into the stem and leaves.
(v) Photosynthesis: As the shoot emerges and develops leaves, the plant is able to carry out photosynthesis, which provides it with the energy to continue growing.
(2aii)
(i) Availability of Resources: The availability of food, water, shelter, and suitable habitat directly influences the population size.
(ii) Predation: The presence of predators can limit the population size of organisms as they prey on them, causing a decrease in the population.
(iii) Competition: Competition for limited resources, such as food and territory, can limit the population size of organisms as individuals have to compete for these resources.
(iv) Disease and Parasites: The presence of diseases and parasites can negatively impact the population size by causing morbidity and mortality.
(2bi)
-Bush Burning-
(PICK ANY TWO)
(i) Loss of vegetation: Bush burning destroys plants, resulting in a loss of habitat and decreased biodiversity.
(ii) Soil degradation: Intense heat from bush burning can lead to soil degradation, reducing its fertility and ability to support plant growth.
(iii) Air pollution: Bush burning releases large amounts of smoke and pollutants into the air, contributing to air pollution and affecting air quality.
(iv) Disruption of natural cycles: Bush burning can disrupt natural ecological cycles, such as nutrient cycling and succession.
-Fertilizer Application-
(PICK ANY TWO)
(i) Eutrophication: Overuse or improper application of fertilizers can lead to eutrophication, where excessive nutrients enter water bodies, leading to algal blooms and oxygen depletion.
(ii) Soil pollution: Certain fertilizers can contain harmful chemicals that can pollute the soil, affecting soil quality and the health of organisms living in it.
(iii) Biodiversity loss: Fertilizer application can favor the growth of certain plant species, leading to a decrease in biodiversity as they outcompete other species.
(iv) Water pollution: Runoff from excessive fertilizer application can enter water bodies, contaminating them and affecting aquatic ecosystems.
-Use of Pesticides-
(PICK ANY TWO)
(i) Harm to non-target organisms: Pesticides can harm not only the targeted pests but also beneficial organisms such as pollinators, natural predators, and soil organisms, affecting biodiversity.
(ii) Bioaccumulation and biomagnification: Some pesticides can accumulate in the body tissues of organisms and can become more concentrated as they move up the food chain, posing a risk to higher-level consumers.
(iii) Soil and water contamination: Pesticides can leach into the soil and be carried into groundwater or runoff into water bodies, causing pollution and affecting aquatic ecosystems.
(iv) Development of pesticide resistance: Overuse of pesticides can lead to the development of resistance in target pests, making them harder to control and requiring stronger and potentially more harmful pesticides.
(2bii)
(i) Pulmonary Respiration
(ii) Cutaneous Respiration
(iii) Buccopharyngeal Respiration
(3ai)
DRAW THE DIAGRAM [https://i.ibb.co/ncCqcfJ/bio3ai.jpg]
(3aii)
(PICK ANY TWO)
(i) Yeast is commonly used in the production of bread to make it rise.
(ii) Yeast plays a crucial role in the fermentation process of brewing beer and making wine.
(iii) Yeast is used in the production of bioethanol, a renewable source of energy.
(iv) Yeast is used to produce various pharmaceutical products, including vaccines, enzymes, and antibiotics.
(3bi)
-Xylem:
(PICK ANY ONE)
(i) It Transports water and nutrients from the roots to the leaves of the plant.
(ii) It provides mechanical support to the plant.
(iii) It facilitates the movement of minerals and hormones within the plant.
(iv) It helps in the process of photosynthesis by supplying water to the leaves.
-Phloem:
(PICK ANY ONE)
(i) It transports organic materials such as sugars and amino acids from the leaves to other parts of the plant.
(ii) It provides a pathway for the distribution of nutrients and hormones throughout the plant.
(iii) It helps in the process of growth and development of the plant.
(iv) It allows for the storage and distribution of carbohydrates in the plant.
-Artery:
(PICK ANY ONE)
(i) It carries oxygenated blood from the heart to the tissues and organs of the body.
(ii) It distributes nutrients, hormones, and other substances to different parts of the body.
(iii) It helps regulate blood pressure through the contraction and relaxation of its smooth muscle walls.
(iv) It facilitates the removal of waste products, such as carbon dioxide, from the tissues.
-Vein:
(PICK ANY ONE)
(i) It carries deoxygenated blood from the tissues and organs of the body back to the heart.
(ii) It assists in the removal of waste products, such as carbon dioxide, from the tissues.
(iii) It returns excess fluids and proteins back to the bloodstream.
(iv) It helps regulate blood flow and maintain blood pressure.
(3bii)
(PICK ANY THREE)
(i) Water and nutrient uptake: Transpiration facilitates the movement of water and nutrients from the roots to the leaves of plants. As water is lost through transpiration, it creates a lower pressure in the leaf cells, which pulls water and nutrients up from the roots.
(ii) Cooling effect: Transpiration helps to cool down plants by evaporating water from the leaves. This process, known as evaporative cooling, helps regulate the temperature of plant tissues and prevents overheating.
(iii) Photosynthesis: Transpiration provides the necessary water for the process of photosynthesis. Water is one of the essential components for photosynthesis, and without transpiration, plants would not be able to produce glucose and oxygen.
(iv) Plant structure and support: Transpiration plays a role in maintaining plant structure and supporting tall plants. As water is lost through transpiration, it creates a negative pressure in the xylem vessels, which helps to pull water and provide support to the plant.
(v) Transport of minerals: Transpiration creates a continuous flow of water and minerals from the roots to other parts of the plant. This transport system ensures that essential minerals, such as nitrogen and phosphorus, are distributed evenly throughout the plant for growth and development.
(3biii)
(i) Use of contraceptive pills
(ii) Use of condoms
(iii) Use of intrauterine devices (IUDs)
NUMBER FOUR
(4ai)
(PICK ANY THREE)
(i) Binoculars
(ii) Camera traps
(iii) GPS trackers
(iv) Transect tapes
(v) Infrared cameras
(4aii)
(i) Resting membrane potential: When a neuron is at rest, there is a separation of charges across the cell membrane, with a higher concentration of positive ions (such as sodium, Na+) outside the cell and a higher concentration of negative ions (such as chloride, Cl-) inside the cell. This results in a resting membrane potential of around -70 millivolts (mV).
(ii) Depolarization: When a stimulus is received by the neuron, it causes changes in the permeability of the cell membrane, allowing positive ions (primarily Na+) to flow into the neuron. This influx of positive ions depolarizes the cell membrane, making the inside of the neuron more positive.
(iii) Action potential: If the depolarization reaches a certain threshold, it triggers the opening of voltage-gated sodium channels in the cell membrane. This allows a rapid influx of sodium ions into the neuron, causing a rapid increase in membrane potential and generating an action potential.
(iv) Repolarization: After the action potential is generated, voltage-gated potassium channels open, allowing potassium ions (K+) to flow out of the neuron. This results in the restoration of the negative charge inside the neuron and repolarization of the cell membrane.
(v) Hyperpolarization: The movement of potassium ions continues briefly after repolarization, causing an overshoot and hyperpolarization of the cell membrane, making the inside of the neuron more negative than its resting state.
(vi) Sodium-potassium pump: To restore the ion concentrations to their original state, a sodium-potassium pump actively transports sodium ions out of the neuron and potassium ions back in. This process requires ATP as a source of energy.
(4bi)
(PICK ANY TWO)
(i) Myopia (nearsightedness): A condition where distant objects appear blurry, while close objects are seen clearly.
(ii) Hyperopia (farsightedness): A condition where close objects appear blurred, while distant objects can be seen more clearly.
(iii) Astigmatism: A condition where the cornea or lens is irregularly shaped, causing blurred or distorted vision at all distances.
(iv) Presbyopia: A condition that occurs with age, resulting in difficulty focusing on close objects.
(4bii)
(PICK ANY FOUR)
(i) Petals
(ii) Sepals
(iii) Stamens
(iv) Carpels
(v) Ovary
(vi) Stigma
(4biii)
Grass –>> Grasshopper –>> Lizard –>> Snake
NUMBER FIVE
(5ai)
(PICK ANY FOUR)
(i) Water
(ii) Oxygen
(iii) Temperature
(iv) Light m
(v) Soil or substrate
(vi) Time
(5aii)
In Tabular form
-Hormonal Coordination-
(PICK ANY THERE)
(i) Hormones are chemical messengers secreted by endocrine glands and released into the bloodstream.
(ii) Hormonal responses are slower and more gradual compared to nervous responses.
(iii) Hormonal responses are often long-lasting.
(iv) Hormonal communication is based on the release and diffusion of hormones throughout the body.
(v) Hormones act on specific target cells or organs that have appropriate receptors.
(vi) Hormonal coordination controls processes such as growth, development, reproduction, and metabolism.
-Nervous Coordination-
(PICK ANY THREE)
(i) Nerves are specialized cells that transmit electrical impulses rapidly.
(ii) Nervous responses are rapid and immediate.
(iii) Nervous responses are often short-lived.
(iv) Nervous coordination is based on the transmission of electrical signals along nerve cells.
(v) Nerves directly connect specific cells, tissues, and organs.
(vi) Nervous coordination controls processes such as movement, sensation, and reflex actions.
(5bi)
(i) Inhalation: Before exhalation, there is an inhalation phase where the diaphragm contracts and moves downward. This causes the volume of the chest cavity to increase and the lungs to expand, allowing air to enter.
(ii) Oxygen exchange: During inhalation, oxygen from the inhaled air passes through the respiratory system’s airways and reaches the alveoli. In the alveoli, oxygen diffuses into the capillaries, where it binds to hemoglobin in red blood cells.
(iii) Carbon dioxide removal: Simultaneously, carbon dioxide, a waste product of cellular respiration, diffuses from the capillaries into the alveoli.
(iv) Exhalation: After oxygen and carbon dioxide exchange, the diaphragm relaxes and moves upward, reducing the volume of the chest cavity. This forces air out of the lungs.
(v) Exhaled air: The exhaled air contains mainly carbon dioxide, along with trace amounts of other gases.
(5bii)
(i) Succulence: Xerophytic plants have adapted to store water in their leaves, stems, or roots to survive in arid environments. They may have fleshy, water-storing tissues or specialized structures to reduce water loss.
(ii) Reduced leaf surface: Many xerophytic plants have smaller or modified leaves, such as spines or scales, to minimize water loss through transpiration.
(iii) Deep-rooted: Xerophytic plants often have deep and extensive root systems to reach underground water sources.
(iv) Waxy or hairy surfaces: Xerophytic plants may have a waxy cuticle or hairy surfaces on their leaves to reduce water loss through evaporation.
(v) CAM metabolism: Some xerophytic plants employ Crassulacean acid metabolism (CAM) photosynthesis, a specialized pathway that allows them to open their stomata at night, reducing water loss during the day.
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