2023 NABTEB GCE Biology Objective & Essay Answers – Nov/Dec

2024 Free NABTEB Expo Questions And Answers

BIOLOGY- OBJ
01-10: CCCCCCDABA
11-20: BAABCDAACD
21-30: ADCACBABCA
31-40: AACBAABBCC
41-50: DCABCCDAAB

COMPLETED
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BIOLOGY- ESSAY ANSWERS
INSTRUCTIONS: ANSWER FOUR(4) QUESTIONS ONLY, AT LEAST ONE QUESTION FROM EACH PART

PART I
(1a)
(i) Number of parents
(ii) Genetic variation
(iii) Speed of reproduction

(1b)
(i) Cellular Organization
(ii) Metabolism
(iii) Homeostasis
(iv) Response to stimuli

– Metabolism: Living organisms carry out metabolic processes, including the conversion of energy from one form to another. Metabolism involves anabolism (building up molecules) and catabolism (breaking down molecules). These processes are essential for the growth, maintenance, and reproduction of organisms.

– Homeostasis: Living organisms have the ability to regulate their internal environment to maintain a stable and balanced condition. Homeostasis is crucial for the proper functioning of cells and is achieved through various physiological processes that control factors such as temperature, pH, and nutrient levels.

(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 important nutrients and minerals. This can happen due to excessive rainfall or irrigation. As the water percolates through the soil, it can wash away nutrients like nitrogen, phosphorus, and potassium, making the soil less fertile over time.

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(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)(check the diagram 👇 )

(3bi)
(i) Broad leaves
(ii) Net-like veins

(3bii)
(i) Narrow leaves
(ii) Parallel veins

(3c)
(I)Petals: They attract pollinators, such as bees or butterflies, with their bright colours and sweet scents.
(II)Sepals: They protect the developing flower bud and provide support to the petals.
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PART III
(4ai)
Anaerobic respiration in plants:
C₆H₁₂O₆ —> 2C₂H₅OH + 2CO₂

(4aii)
Anaerobic respiration in animals:
C₆H₁₂O₆ —> 2C₃H₆O₃

(4b) (Check the diagram below)

(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.
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(5a)
(i) Tricuspid: Its function is to prevent the backflow of blood from the right ventricle to the right atrium during ventricular contraction.
(ii) Bicuspid valve,m: Its function is to prevent the backflow of blood from the left ventricle to the left atrium during ventricular contraction.
(iii) Cardiac sphincter: Its function is to prevent the backflow of stomach acid and partially digested food from the stomach into the esophagus.
(iv) Hepatic portal vein: Its function is to deliver absorbed nutrients from the intestines to the liver for processing and distribution to the rest of the body.
(v) Pulmonary artery: Its function is to transport the blood to the lungs for oxygenation and removal of carbon dioxide.

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(5bi)
(i)Liver: Hepatitis, Cirrhosis
(ii)Kidney: Kidney stones, Chronic kidney disease

(5bii)
Hepatitis is a disease characterized by inflammation of the liver. It can be caused by viral infections (such as hepatitis A, B, or C), alcohol abuse, or autoimmune disorders. Hepatitis can lead to liver damage, scarring, and impaired liver function.

Chronic kidney disease is a progressive condition in which the kidneys gradually lose their ability to filter waste products from the blood. This can result from various factors such as high blood pressure, diabetes, or chronic infections. As kidney function declines, waste products and fluid can build up in the body, leading to complications like electrolyte imbalances and fluid retention.

(5c)
(i) Liver: hepatocytes.
(ii) Kidney: nephrons
(iii) Muscle: myocytes or muscle fibers.
(iv) Nervous system: neurons and glial cells.
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(6a)
(i) A food chain is a linear sequence of organisms in which each organism serves as a source of food for the next organism.

(6aii) (check diagram below)

(6b)
(i) Hemophilia, color blindness, Duchenne muscular dystrophy

(ii) Co-dominance occurs when both alleles in a heterozygous individual are expressed equally, resulting in a phenotype that shows traits from both alleles WHILE Incomplete dominance occurs when the phenotype of the heterozygous individual is an intermediate blend of the two alleles.

(6c)
A woman who is blood type O is advised not to marry a man who has the rhesus factor (Rh-positive) if she is Rh-negative. This is because if the woman is Rh-negative and the man is Rh-positive, there is a risk of incompatibility between their blood types during pregnancy. If the woman becomes pregnant with an Rh-positive baby, her body may develop antibodies against the baby’s Rh-positive blood, potentially leading to complications in future pregnancies. This condition is known as Rh incompatibility or Rh disease.
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