NABTEB GCE 2023 BIOLOGY ANSWERS
INSTRUCTION; ANSWER FOUR(4) QUESTIONS ONLY, AT LEAST ONE QUESTION FROM EACH PART
PART I
(1a)
(i) Methods of Reproduction
(ii) Genetic variation
(iii) Offspring quantity
(1b)
(i) Cellular Organization
(ii) Response to Stimuli
(iii) Metabolism
(iv) Growth and Development
(i) Cellular Organization: Living organisms are composed of one or more cells. Cells are the basic structural and functional units of life. They carry out essential processes such as metabolism, growth, and reproduction.
(ii) Metabolism: Living organisms have the ability to obtain and utilize energy from their environment. They undergo various chemical reactions to convert nutrients into energy for growth, repair, and other life processes.
(1c)
Budding yeast refers to a type of yeast that reproduces through a process called budding. It is a form of asexual reproduction where a small daughter cell, or bud, develops on the surface of the parent cell. The bud gradually enlarges until it reaches a size comparable to the parent cell, and then it detaches to become an independent, fully functional yeast cell.
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PART II
(2a)
Soil can lose its fertility through a process called leaching. Leaching occurs when water moves through the soil, carrying away essential nutrients and minerals. When excessive rainfall or irrigation occurs, the water can wash away these nutrients, leaving the soil less fertile. This can be a problem in agricultural areas where nutrient-rich topsoil is eroded, impacting crop growth and productivity. Farmers often use techniques like crop rotation and adding organic matter to replenish the lost nutrients and maintain soil fertility.
(2b)
Percentage of Water = (Initial mass – Dry mass)/Initial mass × 100
Given:
Initial Mass = 30g
Dry Mass = 25g
Substitute these values into the formula:
Percentage of Water = (30g – 25g)/30g ×100
Percentage of Water = (5g/30g) ×100
Percentage of Water = (⅙) ×100
Percentage of Water = 16.67%
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(3a)
Diagram
[img]https://i.ibb.co/L9njpmT/Seed-Cut-Open.jpg[/img]
(3bi)
External features of Rose (Rosa spp.)
I. Leaves with a reticulate venation
II. Taproot system
(3bii)
External features of Lily (Lilium spp.)
I. Parallel Venation in Leaves
II. Fibrous Root System
(3c)
I. Petals: They play a crucial role in attracting pollinators such as bees, butterflies, and birds.
II. Sepals: They play a role in supporting the structure of the flower as it opens.
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PART III
(4ai)
Anaerobic respiration in plants:
C₆H₁₂O₆ —> 2C₂H₅OH + 2CO₂
(4aii)
Anaerobic respiration in animals:
C₆H₁₂O₆ —> 2C₃H₆O₃
(4b)
Diagram
[img]https://i.ibb.co/JQvMxSz/Paramecium-cell.jpg[/img]
(4c)
Aerobic respiration is a biological process that takes place in the presence of oxygen and involves the breakdown of organic molecules, usually glucose, to release energy. The chemical equation for aerobic respiration is as follows:
C₆H₁₂O₆ + 6O₂ —> 6CO₂ + 6H₂O + Energy
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(5a)
(i) Tricuspid Valve: It Prevents the backflow of blood from the right ventricle to the right atrium during the contraction of the heart.
(ii) Bicuspid Valve (Mitral Valve): It prevents the backflow of blood from the left ventricle to the left atrium during the contraction of the heart.
(iii) Cardiac Sphincter: It regulates the passage of food from the esophagus into the stomach and prevents the backflow of stomach contents into the esophagus.
(iv) Hepatic Portal Vein: It transports nutrient-rich blood from the digestive organs (such as the stomach and intestines) to the liver for processing and storage.
(v) Pulmonary Artery: It carries deoxygenated blood from the right ventricle of the heart to the lungs for oxygenation.
(5bi)
i. Liver: Cirrhosis, Hepatitis
ii. Kidney: Chronic Kidney Disease (CKD),
Kidney Stones
(5bii)
(i) Chronic Kidney Disease (CKD): CKD is a condition where the kidneys gradually lose their ability to function properly over time. It is often caused by conditions such as high blood pressure and diabetes. As CKD progresses, the kidneys may not filter waste and excess fluids effectively, leading to a buildup of toxins in the body. Symptoms may include fatigue, swelling, and changes in urination patterns. If left untreated, CKD can result in kidney failure, requiring dialysis or a kidney transplant.
(ii) Cirrhosis (associated with the liver): Cirrhosis is a chronic liver disease characterized by the replacement of healthy liver tissue with scar tissue, impairing liver function. This scarring typically results from long-term liver damage, often caused by conditions such as chronic alcoholism, viral hepatitis, or fatty liver disease. As cirrhosis progresses, the liver loses its ability to function effectively, leading to complications such as portal hypertension, ascites (fluid buildup in the abdomen), and an increased risk of liver failure.
(5c)
(i) Liver: Hepatocytes
(ii) Kidney: Nephrons
(iii) Muscle: Muscle fibers or myocytes
(iv) Nervous System: Neurons
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PART IV
(6a)
A food chain is a linear representation of the feeding relationships among different organisms in an ecosystem, illustrating the transfer of energy as one organism consumes another.
DIAGRAM OF TERRESTRIAL ECOSYSTEM
[img]https://i.ibb.co/XLy4yxY/Food-web.jpg[/img]
(6b)
Three Sex-Linked Diseases:
(i) Hemophilia
(ii) Color blindness
(iii) Duchenne muscular dystrophy
=Difference between Co-dominance and Incomplete Dominance=
In co-dominance, both alleles in a heterozygous individual express their phenotypes simultaneously without blending WHILE In incomplete dominance, the phenotype of the heterozygous individual is an intermediate or blend of the phenotypes of the homozygous individuals.
(6c)
A woman who is blood type O is advised not to marry a man who is Rh-positive (has the rhesus factor) to prevent the risk of hemolytic disease of the newborn (HDN). If the woman is Rh-negative and the man is Rh-positive, there is a possibility that the offspring could inherit Rh-positive blood, which could lead to Rh incompatibility between the mother and the fetus. This condition could result in the mother’s immune system attacking the Rh-positive blood cells of the developing fetus, causing hemolysis (destruction of red blood cells) and potentially leading to serious health issues for the baby. To prevent this, Rh-negative women are often given Rh immunoglobulin injections during pregnancy and after childbirth to prevent the development of antibodies against Rh-positive blood cells.
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