9th Class Biology Chapter # 2 Exercise Solutions – Punjab Board
Biodiversity
9th Class Biology Chapter 2 Solution (MCQs)
1. Which of the following taxonomic ranks represents the broadest rank?
Options:
a) Species
b) Genus
c) Kingdom
✅ d) Domain
Explanation:
Domain is the highest and broadest taxonomic rank in the biological classification system. It includes all life forms grouped into three domains: Archaea, Bacteria, and Eukarya.
2. Which characteristic is unique to organisms in the domain Archaea?
Options:
a) Cell walls made of peptidoglycan
b) Presence of a nucleus
✅ c) Ability to live in extreme environments
Explanation:
Organisms in the domain Archaea are known for surviving in extreme environments, such as hot springs, salt lakes, and acidic or anaerobic conditions. Their cell walls lack peptidoglycan, and they do not have a nucleus (they are prokaryotes).
3. Which of these statements is NOT related to bacteria?
Options:
a) Do not have a nucleus
b) Cell wall made of peptidoglycan
c) Most are heterotrophic
✅ d) Have chlorophyll in their chloroplast
Explanation:
Bacteria do not have chloroplasts; some can perform photosynthesis, but not with chloroplasts. They also lack a nucleus and most are heterotrophic.
4. Which of these organisms belongs to the domain Eukarya?
Options:
a) Escherichia coli
✅ b) Yeast
c) Coronavirus
d) None of the above
Explanation:
Yeast is a unicellular fungus and belongs to Eukarya because it has a true nucleus. E. coli is a bacterium (prokaryote) and coronavirus is a virus (not even a cell).
5. Which of the following is a key characteristic that distinguishes eukaryotic cells from prokaryotic cells?
Options:
a) Lack of a cell wall
✅ b) Presence of a nucleus
c) Absence of ribosomes
d) Small size
Explanation:
Eukaryotic cells have a well-defined nucleus and membrane-bound organelles. Prokaryotes lack a nucleus.
6. Which kingdom includes organisms that are primarily unicellular, eukaryotic, and often heterotrophic?
Options:
a) Archaea
✅ b) Protista
c) Fungi
d) Plantae
Explanation:
The Kingdom Protista includes mostly unicellular eukaryotic organisms. Many of them are heterotrophic, though some can perform photosynthesis.
7. Why are fungi included in heterotrophic organisms?
Options:
a) Have chitin in cell wall
✅ b) Absorb nutrients
c) Reproduce by spores
d) Cannot prepare food
Explanation:
Fungi are heterotrophs because they absorb nutrients from their surroundings. They don’t perform photosynthesis.
8. Why is it impossible to classify viruses within traditional biological kingdoms?
Options:
✅ a) They lack cell structure and organelles
b) They can perform photosynthesis
c) They are smaller in size than bacteria
d) They are parasites
Explanation:
Viruses do not have cell structure, organelles, or metabolism. Therefore, they don’t fit into any traditional kingdom like plants, animals, or bacteria.
9. Which of the following is the correct way for writing the scientific name of humans?
Options:
✅ a) Homo sapiens
b) Homo sapiens
c) Homo Sapiens
d) homo sapiens
Explanation:
In binomial nomenclature, the first word (genus) is capitalized and the second word (species) is in lowercase. The name should also be italicized or underlined when handwritten.
10. Which information can you get if you know the scientific name of an organism?
Options:
a) Kingdom and phylum
b) Phylum and genus
✅ c) Genus and species
d) Class and species
Explanation:
A scientific name includes the Genus and Species of the organism, e.g., Homo sapiens — where Homo is genus and sapiens is species.
9th Class Biology Chapter 2 Solution Mcqs Complete.
9th Class Biology Chapter 2 Solution Short Answer Questions
1. What is the term used to describe the variety of organisms in ecosystems?
Answer:
The term is biodiversity, which refers to the variety of life forms including plants, animals, fungi, and microorganisms in an ecosystem.
2. How is biodiversity crucial for humans and for the planet Earth?
Answer:
Biodiversity provides food, medicine, clean air, water purification, and ecosystem stability. It ensures survival of life by maintaining natural balance.
3. What are the seven taxonomic ranks used in the Linnaean system?
Answer:
Kingdom
Phylum
Class
Order
Family
Genus
Species
4. Write the taxonomic ranks of lion and corn.
Answer:
Lion (Panthera leo):
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Felidae
Genus: Panthera
Species: leo
Corn (Zea mays):
Kingdom: Plantae
Phylum: Angiosperms
Class: Monocots
Order: Poales
Family: Poaceae
Genus: Zea
Species: mays
5. What are the basic differences between Archaea and Bacteria?
Answer:
Archaea: Live in extreme environments, lack peptidoglycan in cell wall, have unique enzymes and RNA.
Bacteria: Live in common environments, have peptidoglycan in cell wall, differ in genetic structure.
6. What are the shortcomings of the three-kingdom classification system?
Answer:
It did not account for microorganisms.
Grouped unrelated organisms together.
Couldn’t classify unicellular and prokaryotic organisms accurately.
7. Which kingdom includes organisms that are multicellular and heterotrophic, and lack cell walls?
Answer:
Kingdom Animalia
8. Enlist the distinguishing characteristics of fungi.
Answer:
Eukaryotic
Cell walls made of chitin
Heterotrophic (absorb nutrients)
Reproduce via spores
Mostly multicellular (except yeast)
9. List the three domains that encompass all living organisms.
Answer:
Archaea
Bacteria
Eukarya
10. Why can’t we classify viruses in any kingdom?
Answer:
Viruses lack cellular structure, do not perform metabolism, and can’t reproduce on their own. Therefore, they don’t fit into any traditional kingdom.
11. How does binomial nomenclature facilitate communication about organisms across different languages?
Answer:
It provides a universal scientific name (Genus + species) that is understood globally, regardless of local language differences, reducing confusion.
9th Class Biology Chapter 2 Solution Short Question Complete.
9th Class Biology Chapter 2 Solution in Detail
1. Discuss biodiversity and its significance in maintaining the health of ecosystems.
Answer:
Biodiversity refers to the wide variety of living organisms on Earth, including animals, plants, fungi, and microorganisms. It plays a crucial role in maintaining the health and stability of ecosystems by:
Maintaining food chains and food webs, which ensure the survival of all species through interdependence.
Supporting pollination of crops and wild plants by insects, birds, and other animals.
Improving soil fertility through the action of decomposers like fungi and bacteria that recycle nutrients.
Purifying air and water by the activity of plants and microbes that filter harmful substances.
Providing resilience against climate change by allowing ecosystems to adapt and recover from disturbances.
Ensuring sustainability: Ecosystems with high biodiversity are more productive, stable, and resistant to environmental threats.
In short, biodiversity is the foundation of ecosystem services that humans and other life forms depend on for survival.
2. Explain the importance of classification in biology and how it helps us understand the relationships between different organisms.
Answer:
Classification is the systematic arrangement of organisms into groups based on similarities and differences. It is important in biology for several reasons:
Makes study easier: By grouping organisms, it simplifies the study of millions of living species.
Reveals evolutionary relationships: Classification reflects how species have evolved from common ancestors.
Enables identification: Scientists and researchers can easily identify and differentiate organisms.
Predicts characteristics: Once an organism is classified, its traits can be predicted based on others in the same group.
Supports scientific communication: Universal classification reduces confusion across different languages and regions.
Thus, classification helps build a logical structure in biology and deepens our understanding of life’s diversity.
3. Describe the Linnaean system of classification in detail, stating the seven taxonomic ranks and their relationships.
Answer:
The Linnaean system, developed by Carl Linnaeus, is a hierarchical system used to classify living organisms. It consists of seven major ranks, from broadest to most specific:
Kingdom – the largest and most inclusive category.
Phylum – groups organisms with similar body plans.
Class – organisms in a phylum with common traits.
Order – a further division based on specific characteristics.
Family – more closely related organisms.
Genus – closely related species grouped together.
Species – the most specific level; organisms that can interbreed.
Each rank shares common features, and as we move down the hierarchy, organisms become more similar to each other. This system allows for precise naming and understanding of relationships among species.
4. Compare and contrast the domains Archaea and Bacteria, focusing on their key characteristics.
Answer:
| Feature | Archaea | Bacteria |
|---|---|---|
| Cell Wall | No peptidoglycan | Peptidoglycan present |
| Habitat | Extreme environments (hot, salty, acidic) | Common environments (soil, water, body) |
| Membrane Lipids | Unique and branched | Unbranched and typical |
| Genetic Material | Closer to Eukaryotes | Distinct from both Archaea and Eukarya |
| Antibiotic Sensitivity | Usually resistant | Usually sensitive |
Archaea and Bacteria are both prokaryotic and unicellular, but differ significantly in their cell structure, habitats, and genetics.
5. Describe the diagnostic characteristics of the four kingdoms within the domain Eukarya.
Answer:
Kingdom Protista
Mostly unicellular
Eukaryotic with nucleus
Live in aquatic environments
Can be autotrophic or heterotrophic
Kingdom Fungi
Eukaryotic and mostly multicellular (except yeast)
Cell walls made of chitin
Heterotrophic (absorb nutrients)
Reproduce via spores
Kingdom Plantae
Multicellular and autotrophic
Have chlorophyll and perform photosynthesis
Cell walls made of cellulose
Stationary organisms
Kingdom Animalia
Multicellular and heterotrophic
No cell walls
Highly developed nervous and muscular systems
Most reproduce sexually
6. Discuss the challenges of classifying viruses within the traditional three-domain system of life.
Answer:
Viruses present a unique challenge to classification because they do not share key characteristics of living organisms. Some major reasons include:
Lack of cellular structure – viruses are not made of cells.
No metabolism – they do not carry out life processes on their own.
Reproduction depends on host cells – viruses cannot replicate without invading a living cell.
Do not grow or respond to stimuli – unlike true living organisms.
Because of these reasons, viruses do not fit into the domains Archaea, Bacteria, or Eukarya, and are instead classified separately, often considered on the borderline between living and non-living.
7. Explain the rules and guidelines for suggesting scientific names to organisms.
Answer:
Scientific names are given according to the rules of binomial nomenclature developed by Linnaeus. The key rules are:
Two-part name: The name consists of Genus and species.
Genus capitalized, species lowercase: e.g., Homo sapiens.
Written in italics (or underlined when handwritten).
Use of Latin or Greek: Names are usually derived from classical languages.
Must be unique: The name should not duplicate an existing one.
Approved by international codes: Such as the International Code of Zoological Nomenclature (ICZN) or Botanical Nomenclature (ICBN).
This universal naming system reduces confusion and allows scientists across the world to communicate clearly.
9th Class Biology Chapter 2 Solution Detail answer Complete.
9th Class Biology Chapter 2 Solution Inquisitive Questions
1. How might placing an organism in the incorrect taxonomic group affect conservation or scientific studies?
Detailed Answer:
Accurate classification of organisms is essential for scientific understanding and for making informed decisions in conservation, agriculture, and medicine. Placing an organism in the wrong taxonomic group can have serious consequences:
Conservation Errors
Misidentifying a species may lead to inaccurate assessment of its population status.
A rare or endangered species might be mistaken for a common one, and thus not given legal protection or funding for conservation.
It may also cause misallocation of resources, protecting non-threatened organisms instead of endangered ones.
Medical and Pharmaceutical Risks
Many medicines are derived from natural organisms. If a species is misclassified, researchers might use the wrong organism for drug development, leading to ineffective or harmful treatments.
For example, using a wrongly identified plant for herbal medicine can lead to allergic reactions or poisoning.
Incorrect Scientific Research and Data
Biological studies rely on correct identification. Misclassification can cause flawed research outcomes, affecting genetics, evolution, or ecology-related studies.
It can also mislead future studies, spreading false data across literature and causing delays in scientific progress.
Harm to Ecosystems
Conservation planning might involve introducing organisms for ecosystem restoration. If a misclassified species is introduced, it might become invasive or harmful, disrupting native biodiversity.
Conclusion:
Incorrect classification doesn’t just affect academics — it can lead to real-world consequences in environmental protection, health, and sustainable development. That’s why accurate taxonomy is critical for all areas of biological science.
2. Imagine you discover a new organism. What steps would you take to classify and name it according to the principles of binomial nomenclature?
Detailed Answer:
If a new organism is discovered, a systematic and internationally accepted process must be followed to classify and name it scientifically. The steps are:
Detailed Observation and Description
Study the organism’s morphology (shape, size, color, structure), behavior, and habitat.
Examine its cellular structure (is it prokaryotic or eukaryotic?) and reproductive methods.
Genetic and Biochemical Analysis
Perform DNA sequencing and biochemical tests to understand how it is related to known organisms.
Compare these findings to existing species databases.
Determine its Taxonomic Placement
Based on the similarities and differences, determine which Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species it belongs to.
This helps in placing the organism accurately in the biological hierarchy.
Assign a Scientific Name (Binomial Nomenclature)
Use the Latin or Greek language to create a name that describes a distinctive feature, place of discovery, or honors a person.
The name must follow the format:
Genus name: Capitalized
Species name: Lowercase
Example: Rosa indica (Rose from India)
The full name should be italicized or underlined when handwritten.
Follow Naming Rules (ICZN/ICBN)
Ensure the name is not already used.
The name should be unique, descriptive, and accepted by the International Code of Nomenclature for animals, plants, fungi, or microbes.
Publish and Submit for Approval
Write a formal scientific description and publish it in a recognized scientific journal.
Submit it to the appropriate taxonomic committee for validation and international acceptance.
Conclusion:
Naming a new organism is not just about giving it a label — it’s a scientific responsibility that ensures the organism is recognized globally, and its data can be used accurately in research, conservation, and education.
9th Class Biology Chapter 2 Solution Inquisitive Question Complete.
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