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# IJMB Biology Paper 1 2023 Questions And Answers

The Interim Joint Matriculation Board Examination (IJMB) has scheduled IJMB Biology Paper 1 2023 Questions And Answers to Kick off on Tuesday 19th – April – 2023.

## IJMB Biology Paper 1 2023 Questions And Answers

(1i)
Range = Maximum Value – Minimum Value

COLUMN: 0 mg/g
Range: 9 – 4 = 5

COLUMN: 5 mg/g
Range: 9 – 6 = 3

COLUMN: 10 mg/g
Range: 9 – 7 = 2

COLUMN: 20 mg/g Range: 12 – 7 = 5

(1ii)
Arithmetic Mean = (Sum of all values) / (Number of values

COLUMN: 0 mg/g
Mean: (8 + 4 + 6 + 7 + 6 + 5 + 8 + 9 + 5 + 5) / 10 = 6.3

COLUMN: 5 mg/g
Mean: (7 + 8 + 7 + 9 + 8 + 7 + 6 + 7 + 8 + 9) / 10 = 7.8

COLUMN: 10 mg/g
Mean: (9 + 8 + 9 + 8 + 7 + 9 + 8 + 9 + 9 + 9) / 10 = 8.5

COLUMN: 20 mg/g
Mean: (10 + 9 + 9 + 10 + 11 + 12 + 9 + 7 + 9 + 8) / 10 = 9.4

COLUMN: 40 mg/g
Mean: (9 + 7 + 7 + 6 + 7 + 8 + 6 + 6 + 7 + 8) / 10 = 7.1

(1iii)
Diagram

(1iv)
To find the median number of pods produced by each treatment, arrange the values in each column in ascending order and find the middle value:

COLUMN: 0 mg/g
Median: (5 + 5) / 2 = 5

COLUMN: 5 mg/g
Median: (7 + 7) / 2 = 7

COLUMN: 10 mg/g
Median: (9 + 9) / 2 = 9

COLUMN: 20 mg/g
Median: (9 + 10) / 2 = 9.5

COLUMN: 40 mg/g
Median: (7 + 7) / 2 = 7

(1v)
Modal value : This is the value that appears most frequently in each column:

COLUMN: 0 mg/g
Modal number: 5

COLUMN: 5 mg/g
Modal number: 7

COLUMN: 10 mg/g
Modal number: 9

COLUMN: 20 mg/g
Modal number: 9

COLUMN: 40 mg/g
Modal number: 7

(1vi)
Variance = Σ((x – μ)²) / (n – 1)

where Σ represents the sum, x is the individual value, μ is the mean, and n is the number of values.

For the 10 mg/g treatment:

Mean (μ) = 8.5

Variance = ((9 – 8.5)² + (8 – 8.5)² + (9 – 8.5)² + (8 – 8.5)² + (7 – 8.5)² + (9 – 8.5)² + (8 – 8.5)² + (9 – 8.5)² + (9 – 8.5)² + (9 – 8.5)²) /(10 – 1)

Variance = (0.25 + 0.25 + 0.25 + 0.25 + 1.25 + 0.25 + 0.25 + 0.25 + 0.25 + 0.25) /9
Variance = 4/9
Variance = 0.444

(1vii)
Standard Error = √(Variance / n)

where Variance is the variance calculated in (vi) and n is the number of values.

For the 10 mg/g treatment:
Variance = 4/9
n = 10

Standard Error = √((4 / ) /10)
Standard Error = √(4 /90)
Standard Error ≈ 0.211

QUESTION 2

(2)
(i) Seed bearing vascular plants are referred to as gymnosperms and angiosperms.
(ii) A plastid that stores starch is called amyloplast.
(iii) The arrangement of the calyx and corolla in the floral bud is known as aestivation.
(iv) Heterogamy refers to the type of reproduction in algae in which the male and female gametes are morphologically different.
(v) The spores produced in basidiomycota are called basidiospores.
(vi) Rod shaped bacteria are called bacilli.
(vii) The structure responsible for the absorption of water and nutrients in bryophytes is called the rhizoid.
(viii) The extinct class of the pteridophyta is called the Lycopodiophyta.
(ix) Organisms with membrane bound organelles in their cells are referred to as eukaryotes.
(x) The entire mass of hyphae in fungi is termed mycelium.

(3i)
Conservation of biodiversity: Conservation of biodiversity refers to the protection and sustainable management of the variety of life forms on Earth, including plants, animals, and microorganisms. It involves efforts to maintain the genetic, species, and ecosystem diversity to ensure the long-term viability of ecosystems. Conservation of biodiversity is essential because it supports ecosystem services, such as providing clean air and water, pollination, soil fertility, and climate regulation. It also has intrinsic value, as each species contributes to the overall complexity and resilience of the planet’s ecosystems.

(3ii)
Ecological succession: Ecological succession is the process of change in the species composition and structure of an ecological community over time. It occurs in ecosystems following a disturbance, such as a fire, flood, or the formation of new land. Succession can be primary or secondary. Primary succession starts in areas devoid of life, such as newly formed volcanic rock or glacial retreat, where pioneer species colonize and gradually create conditions for other species to establish. Secondary succession occurs in areas that have been disturbed but still retain soil or remnants of the previous community. Over time, different species replace one another, leading to a more complex and stable community.

(3iii)
Ecosystem: An ecosystem refers to a complex and interconnected community of living organisms (biotic factors) and their physical environment (abiotic factors) in a particular geographic area. It encompasses all the organisms, including plants, animals, microorganisms, and their surrounding physical and chemical components, such as soil, water, air, and nutrients. Ecosystems can vary greatly in size and can be as small as a pond or as large as a biome. They function as a unit, where energy flows through food chains and cycles of matter occur, maintaining a delicate balance.

(3iv)
Food chain: A food chain is a linear sequence that illustrates the transfer of energy and nutrients from one organism to another in an ecosystem. It represents the feeding relationships between different organisms, starting with producers (usually plants or algae) that convert sunlight into food through photosynthesis. The primary consumers, such as herbivores, eat the producers, followed by secondary consumers (carnivores or omnivores) that feed on the herbivores. The energy flow continues with tertiary consumers, and so on, forming a chain of feeding relationships. Each level of the food chain is called a trophic level. Decomposers, such as bacteria and fungi, break down dead organisms and organic matter, returning nutrients to the environment and completing the cycle.

NUMBER 4

(4a)
[TABULATE]

=ALGAE=
(i) Simple plant
(ii) Lack true roots
(iii) Majority are aquatic
(iv) Can contain vascular chlorophyll
(v) Reproduce asexually and sexually
(vi) Do not have specialized structures for water and nutrient absorption
(vii) Lack organized tissues and organs

=BRYOPHYTES=
(i) Complex plant
(ii) Have true steams and leaves
(iii) Majority are terrestrial
(iv) Do not contain vascular tissue
(v) Reproduce asexually and sexually
(vi) Have specialized structures fir water and nutrient absorption
(vii) Have organized tissues and organs for transportation, conduction and support.

(4b)
=TYPES OF LICHENS=
(i) Foliose Lichens: These lichens have flat leaf-like thalli that are loosely attached to the substrate. They often overlap and have a lobed or wavy appearance. Examples include Parmelia and Peltigera.

(ii) Fruticose Lichens: These lichens have branching bushy thalli that resemble miniature shrubs or trees. They are usually tufted or pendulous and can be either upright or hanging from the substrate. Examples include Usnea and Cladonia.

(iii) Crustose Lichens: These lichens have crust-like thalli that are closely attached to the substrate. They form a thin crusty layer that adheres tightly to rocks bark or soil. Examples include Xanthoria and Rhizocarpon.

=RANGE FORMS OF LICHENS=
(i) Squamulose: These lichens have small scale-like structures called squamules that are loosely attached to the substrate. They can be easily detached and scattered by wind or water.

(ii) Microlichen or Microfoliose: These lichens have tiny thalli with a diameter of less than 1 cm. They often form a crust on the substrate and are commonly found in harsh environments such as deserts or high mountain regions.

(iii) Macrolichen or Macrufoliose: These lichens have larger more visible thalli that can range from a few centimeters to several meters in size. They are often found in forested or open areas and can have a variety of forms including leafy shrubby or strap-like.

(iv) Gelatinous: These lichens have gelatinous or jelly-like thalli that are soft and pliable. They can be found growing on rocks tree trunks or other substrates and often have a translucent or waxy appearance.

(v) Crustose-Fruticose Mixture: These lichens have a combination of crustose and fruticose growth forms. They often have a crustose base with fruticose branches or tufts extending from it.

NUMBER FIVE

(5)
(i) Taproots: Many angiosperms have a taproot system where the primary root grows vertically downwards and gives rise to lateral roots. Taproots are common in dicotyledonous plants and provide stability and the ability to reach deeper soil layers for water and nutrients. Plants with taproots include carrots radishes and dandelions.

(ii) Adventitious roots: Adventitious roots are roots that arise from non-root tissues such as stems leaves or even flowers. They can develop from nodes or internodes and serve various functions. Examples of adventitious roots include prop roots in corn and brace roots in sugarcane which provide additional support to the plant.

(iii) Storage roots: Some plants modify their roots to store water and nutrients. These storage roots become enlarged due to the accumulation of starch sugars or other storage substances. Examples include the swollen taproots of carrots or beets which store carbohydrates and the tuberous roots of sweet potatoes which store starch.

(iv) Pneumatophores: Pneumatophores are specialized aerial roots that grow vertically above the ground in wet or waterlogged environments. They are found in plants like mangroves and help facilitate gas exchange between the submerged roots and the atmosphere. Pneumatophores have special pores called lenticels that allow oxygen to enter the roots.

(v) Contractile roots: Contractile roots are modified roots that pull the plant’s stem or bulb deeper into the soil. They shrink or contract by shortening their length which helps anchor the plant and ensure its stability. Lilies and some bulbs like daffodils exhibit this type of root modification.

(vi) Rhizomes: Rhizomes are horizontal underground stems that serve as storage organs and produce new shoots and roots. While not technically roots they function similarly in terms of nutrient storage and vegetative propagation. Plants like ginger iris and bamboo have rhizomes.

(viii) Parasitic roots: Parasitic plants such as mistletoe have specialized roots called haustoria that penetrate and attach to the host plant’s vascular system. These roots extract water nutrients or even carbohydrates from the host plant.

(6a)
EXPLANATORY NOTES ON PHOTOSYNTHESIS

(i) Introduction:
Photosynthesis is a vital process that occurs in plants, algae, and some bacteria. It is the primary means by which energy from sunlight is converted into chemical energy in the form of glucose, which serves as the fuel for all living organisms. This article provides a comprehensive explanation of the process of photosynthesis.

(ii) Definition:
Photosynthesis is a complex process that takes place in the chloroplasts of plant cells. It involves the conversion of carbon dioxide (CO₂) and water (H₂O) into glucose (C₆H₁₂O₆) and oxygen (O₂), using sunlight as the primary source of energy. The process can be summarized by the following equation:
6CO₂ + 6H₂O + sunlight —> C₆H₁₂O₆ + 6O₂

(iii) Key Players:
(a) Chloroplasts: Organelles found in plant cells where photosynthesis occurs. They contain chlorophyll, the primary pigment responsible for capturing light energy.
(b) Chlorophyll: A green pigment found in chloroplasts that absorbs light energy during photosynthesis.
(c) Light energy: Electromagnetic radiation from the sun that is essential for photosynthesis.
(d) Carbon dioxide (CO2): A gas absorbed from the atmosphere and used as a carbon source for photosynthesis.
(e) Water (H2O): Absorbed through the plant’s roots and used as a source of hydrogen and electrons during photosynthesis.
(f) Glucose (C6H12O6): A simple sugar synthesized during photosynthesis that serves as a primary energy source for plants.

(iv) Process of Photosynthesis:
(a) Light-dependent reactions:
(i) Light absorption: Chlorophyll molecules in the chloroplasts absorb light energy.
(ii) Electron transport: The absorbed energy is used to power a series of electron transfer reactions, creating energy-rich molecules (ATP and NADPH).
(iii) Splitting of water: Water molecules are split, releasing oxygen (O₂) as a byproduct and providing electrons and hydrogen ions (H⁺) for the next steps.

(b) Light-independent reactions (Calvin cycle):
(i) Carbon fixation: Carbon dioxide (CO₂) from the atmosphere is combined with hydrogen and electrons from the light-dependent reactions to form a three-carbon compound called 3-phosphoglycerate (PGA).
(ii) Reduction and regeneration: ATP and NADPH produced in the light-dependent reactions are used to convert PGA into glyceraldehyde 3-phosphate (G3P). Some G3P molecules combine to form glucose, while others are recycled to regenerate the starting molecule (RuBP) for future CO₂ fixation.

(v) Factors Affecting Photosynthesis:
(a) Light intensity: Higher light intensity generally increases the rate of photosynthesis until a saturation point is reached.
(b) Carbon dioxide concentration: Increased CO2 levels can enhance photosynthesis, up to a certain threshold.
(c) Temperature: Optimal temperatures within a range promote photosynthesis, but extreme temperatures can disrupt the process.
(d) Water availability: Sufficient water is necessary for photosynthesis to occur efficiently.

(vi) Significance of Photosynthesis:
(a) Oxygen production: Photosynthesis is the primary source of atmospheric oxygen, crucial for the survival of aerobic organisms.
(b) Food production: Photosynthesis provides the foundation for the food chain, as plants are the primary producers of organic compounds that sustain all other organisms.
(c) Energy storage: The glucose produced during photosynthesis serves as a source of energy for plants and is also utilized by animals when they consume plant matter.
(d) Carbon dioxide regulation: Photosynthesis helps regulate atmospheric CO₂ levels, acting as a natural carbon sink that mitigates climate change.

(6b)
(i) Lack of Vascular Tissue: Unlike vascular plants, such as ferns and flowering plants, bryophytes lack specialized tissues for transporting water, nutrients, and sugars throughout the plant. They do not have true roots, stems, or leaves.

(ii) Dominant Gametophyte Generation: Bryophytes have a life cycle that alternates between two generations, the gametophyte and sporophyte. The gametophyte generation is the dominant and independent stage, while the sporophyte generation is dependent on the gametophyte.

(iii) Small Size: Bryophytes are typically small in size, ranging from a few millimeters to a few centimeters in height. Their small stature is due to the absence of vascular tissue, which limits their ability to transport water and nutrients over long distances.

(iv) Moisture Dependency: Bryophytes require a moist environment to survive and reproduce. They lack a protective cuticle on their surfaces and rely on water absorption directly through their cells. This dependency on water is why they are commonly found in damp habitats like forests, wetlands, and along stream banks.

(v) Reproduction through Spores: Bryophytes reproduce by producing spores. The sporophyte generation of the plant produces spore capsules at its tip, which release spores into the environment. These spores germinate to form the gametophyte generation.

(vi) Lack of Seeds and Flowers: Bryophytes do not produce seeds or flowers for reproduction. Instead, they rely on the production of sperm and egg cells, which are produced in separate structures on the gametophyte. The sperm cells require a film of water to swim to the egg cells for fertilization.

(vii) Ecological Importance: Bryophytes play significant roles in ecosystems. They provide important habitats and microenvironments for various organisms, contribute to soil formation, help retain moisture, and play a role in nutrient cycling.

(viii) Environmental Indicators: Due to their sensitivity to changes in environmental conditions, bryophytes are used as ecological indicators. Their presence or absence in certain habitats can provide insights into the health and quality of ecosystems.

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