Class 9 Biology – Chapter 2: Biodiversity

Board: Federal Board (FBISE)

Section I: Multiple Choice Questions

1. Into which kingdom would you place a multicellular land organism that performs photosynthesis?

A) Monera
B) Protista
C) Plantae
D) Animalia

Correct Answer: C) Plantae

2. Which kingdom is mismatched with its characteristics?

A) Fungi – Usually saprotrophic
B) Animalia – Rarely ingestive
C) Protista – Various modes of nutrition
D) Plantae – Photosynthetic

Correct Answer: B) Animalia – Rarely ingestive

Animals are characteristically ingestive heterotrophs.

3. The kingdom to which algae belong is:

A) Animalia
B) Protista
C) Plantae
D) Fungi

Correct Answer: B) Protista

4. Scientific names have the advantage that they:

A) Apply the same name to different organisms.
B) Give the same organisms different names in different areas.
C) Have no scientific basis.
D) Have a scientific basis and are universally accepted.

Correct Answer: D) Have a scientific basis and are universally accepted.

5. Binomial nomenclature was introduced by:

A) Aristotle
B) Carolus Linnaeus
C) Ernest Haeckel
D) R. H. Whittaker

Correct Answer: B) Carolus Linnaeus

6. Organisms that feed on dead and decaying matter are called:

A) Saprotrophs
B) Autotrophs
C) Heterotrophs
D) Parasites

Correct Answer: A) Saprotrophs

7. Viruses are assigned to which kingdom?

A) Plantae
B) Protista
C) Fungi
D) Not included in any kingdom

Correct Answer: D) Not included in any kingdom

8. What is the common characteristic of viruses, prions, and viroids?

A) Respiration
B) Movement
C) Infectious nature
D) Excretion

Correct Answer: C) Infectious nature

9. Colonial organization is a unique feature of which kingdom?

A) Animalia
B) Protista
C) Fungi
D) Plantae

Correct Answer: B) Protista

10. Which option correctly represents the modes of nutrition of the following organisms?

Correct Answer: C) Ingestive | Heterotrophic | Absorptive | Photosynthetic

The sequence is: Animal – Ingestive; Prokaryote – Heterotrophic; Fungi – Absorptive; Plant – Photosynthetic.

11. Viruses are not included in any domain or classification because:

A) They are poorly understood.
B) They are too large.
C) They are of various colours.
D) They are not considered organisms.

Correct Answer: D) They are not considered organisms.

12. A group of related genera consists of:

A) A phylum
B) A class
C) An order
D) A family

Correct Answer: D) A family

13. In binomial nomenclature, which name begins with a capital letter?

A) Genus
B) Class
C) Species
D) Family

Correct Answer: A) Genus

14. If humans and cats belong to the same class, they must belong to the same:

A) Phylum
B) Order
C) Family
D) Genus

Correct Answer: A) Phylum

Section II: Short Answer Questions

1. Why are the following scientists famous?

a) Aristotle

Aristotle classified organisms into two broad groups: plants and animals. He also grouped animals into those with blood and those without blood.

b) Carolus Linnaeus

Carolus Linnaeus developed the system of binomial nomenclature and hierarchical classification.

c) Carl Woese

Carl Woese introduced the Three-Domain System of classification based on ribosomal RNA sequences.

2. Define the following terms:

a) Biodiversity

Biodiversity is the variety and variability of life forms, including plants, animals, and microorganisms, on Earth and the ecological complexes in which they occur.

b) Classification

Classification is the sorting or categorization of organisms into groups and subgroups based on their similarities and evolutionary relationships.

c) Taxonomy

Taxonomy is the branch of biology that deals with the naming, description, and classification of organisms.

d) Systematics

Systematics is the study of the diversification of living forms and the evolutionary relationships among extinct and living organisms.

e) Domain

A domain is the highest taxonomic rank in the biological classification system, above a kingdom.

f) Taxa (Taxon)

Taxa are units or categories of biological classification, such as species, genus, and family. The singular form is taxon.

g) Species

A species is a group of natural populations of organisms that can interbreed freely in nature and produce fertile offspring. They are reproductively isolated from other such groups.

3. What is a domain? Name the three domains of life.

A domain is the highest taxonomic rank, above kingdoms. It separates organisms based on fundamental cellular and genetic differences.

The three domains of life are:

1. Archaea

2. Bacteria

3. Eukarya

4. What are the bases of classification of life into domains?

Classification into domains is primarily based on:

• Ribosomal RNA (rRNA) gene sequences.

• Cellular structure, including the presence or absence of a nuclear membrane.

• The chemical composition of membrane lipids.

5. Differentiate between the following:

a) Bacteria and Protists

Bacteria are prokaryotes that lack a membrane-bound nucleus and membrane-bound organelles. Protists are eukaryotes that possess a true nucleus and membrane-bound organelles.

b) Fungi and Plants

Fungi are heterotrophic, absorptive organisms with cell walls made of chitin. Plants are autotrophic, photosynthetic eukaryotes with cell walls made of cellulose.

c) Plants and Animals

Plants are multicellular autotrophs with cellulose cell walls. Animals are multicellular ingestive heterotrophs that lack cell walls.

6. Answer the following questions with supporting reasons.

a) Which is the simplest domain?

Bacteria or Archaea are the simplest domains because their organisms are unicellular prokaryotes. They lack membrane-bound organelles and complex internal compartmentalization.

b) Which is the most complex domain?

Eukarya is the most complex domain because its organisms possess eukaryotic cells with a nucleus and membrane-bound organelles.

c) Are most bacteria harmful?

No. The vast majority of bacteria are harmless or beneficial. They act as decomposers, form part of the gut flora, and help in nitrogen fixation. Only a small fraction are pathogenic.

d) Which domain can survive in most adverse conditions?

Archaea can survive in extreme conditions. Many are extremophiles that tolerate extreme temperatures, high salinity, and acidic environments.

7. Compare the two-kingdom, three-kingdom, and five-kingdom systems of classification.

Two-Kingdom System

• Proposed by Aristotle and later developed by Linnaeus.

• Divides living organisms into Plantae and Animalia.

• It failed to accommodate microorganisms such as bacteria and fungi properly.

Three-Kingdom System

• Proposed by Ernst Haeckel in 1866.

• Added the kingdom Protista to accommodate unicellular organisms.

Five-Kingdom System

• Proposed by R. H. Whittaker in 1969 and later modified by Margulis and Schwartz.

• Divides organisms into Monera, Protista, Fungi, Plantae, and Animalia.

• Classification is based on cellular organization and modes of nutrition.

8. Compare the three-domain system of classification.

The three-domain system divides cellular life into three domains:

1. Archaea: Consists of prokaryotic organisms that differ from bacteria in cell wall composition, membrane lipids, and ribosomal RNA genetics.

2. Bacteria: Consists of prokaryotic organisms with distinctive cellular characteristics.

3. Eukarya: Includes organisms with eukaryotic cells containing a true nucleus and membrane-bound organelles.

Archaea and Bacteria are both prokaryotic, but Archaea differ significantly from Bacteria in their cellular and molecular characteristics. Archaea are considered evolutionarily closer to Eukarya.

9. Why is a mule not regarded as a species?

A mule is the sterile offspring of a male donkey and a female horse. Mules generally cannot produce fertile offspring. Therefore, they do not meet the biological definition of a species, which requires organisms to interbreed naturally and produce fertile descendants.

10. Complete the following chart.

The supplied material gives the following information for completing the classification chart:

• Top-left box: Prokaryotes (or Monera)

• Top-right box: Eukaryotes (or Eukarya kingdoms)

The branching diagram follows these characteristics:

• Unicellular organisms → Prokaryotes

• Multicellular organisms → Eukaryotes

• Photosynthetic organisms → Plants

• Non-photosynthetic organisms → Fungi and Animals

Note: The original chart image was not included in the supplied material, so only the provided labels and branching information are reproduced here.

Section III: Extensive Answer Questions

1. What is biodiversity? Write the importance of biodiversity in the natural ecosystem.

Biodiversity refers to the total variety of genes, species, and ecosystems in a particular region.

Importance of Biodiversity

1. It maintains ecosystem stability and resilience.

2. It provides food, medicines, and industrial raw materials.

3. It regulates climate, purifies air and water, and supports nutrient cycling.

4. It supports pollination and maintains soil fertility.

2. Describe classification. How are organisms classified?

Classification is the systematic arrangement of organisms into hierarchical groups based on their shared characteristics and evolutionary history.

Organisms are classified by comparing their morphological, anatomical, genetic, and biochemical similarities.

They are arranged into the following taxonomic ranks:

Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species

3. What are the main aims and objectives of classification?

The main aims and objectives of classification are:

1. To determine evolutionary relationships (phylogeny) among organisms.

2. To make the study of millions of diverse living organisms easier and more manageable.

3. To provide universal identification and scientific names for organisms.

4. Give an account of the history of classification.

The classification of living organisms developed through the contributions of several scientists.

Aristotle: Classified living organisms into two broad groups: plants and animals.

Abu Usman Umer Al-Jahiz: Described the characteristics of approximately 350 species of animals and studied animal behaviour.

Andrea Cesalpino and John Ray: Introduced advanced methods of grouping plants.

Carolus Linnaeus: Formulated binomial nomenclature and developed hierarchical taxonomy.

Haeckel, Chatton, Copeland, Whittaker, and Woese: Contributed to the development of modern classification systems, progressing from two kingdoms to five kingdoms and finally to three domains based on cellular and molecular discoveries.

5. What are the characteristics of the domain Archaea?

The main characteristics of Archaea are:

1. They are ancient prokaryotes, many of which are adapted to extreme environments.

2. Some are extremophiles, including:

   • Halophiles: Live in environments with high salt concentrations.

   • Thermophiles: Survive in extremely hot environments.

   • Methanogens: Produce methane.

3. Their cell walls lack peptidoglycan.

4. They possess unique membrane lipids and distinct ribosomal RNA sequences.

6. What are the characteristics of the domains (a) Bacteria and (b) Eukarya?

a) Bacteria

1. Bacteria are unicellular prokaryotic organisms.

2. Their cell walls contain peptidoglycan.

3. They are found in a wide range of environments.

b) Eukarya

1. Eukarya includes organisms with eukaryotic cells.

2. Their cells contain a true nucleus and membrane-bound organelles.

3. This domain includes single-celled protists and complex multicellular fungi, plants, and animals.

7. What are the diagnostic characteristics of the four kingdoms of domain Eukarya?

1. Protista

• Mostly unicellular or simple multicellular eukaryotes.

• Includes organisms such as algae and protozoa.

• Shows diverse modes of nutrition.

2. Fungi

• Includes unicellular and multicellular heterotrophic eukaryotes.

• Their cell walls contain chitin.

• They obtain nutrients through absorption.

3. Plantae

• Consists of multicellular autotrophic eukaryotes.

• Their cell walls contain cellulose.

• They perform photosynthesis.

4. Animalia

• Consists of multicellular ingestive heterotrophic eukaryotes.

• Their cells lack cell walls.

8. Describe the taxonomic ranks of classification.

The hierarchical taxonomic ranks, from the broadest to the most specific, are:

1. Domain: The highest taxonomic rank.

2. Kingdom: A major group within a domain.

3. Phylum: A group of related classes. In plants, the term division is also used.

4. Class: A group of related orders.

5. Order: A group of related families.

6. Family: A group of related genera.

7. Genus: A group of closely related species.

8. Species: The basic and fundamental unit of classification.

9. Write a brief note on species.

A species is the basic unit of biological classification. It consists of a group of organisms capable of interbreeding naturally and producing fertile offspring.

Members of a species share a common gene pool, similar morphological characteristics, and a common evolutionary lineage.

10. What is binomial nomenclature? Describe its aims, principles, and importance using local examples.

Binomial Nomenclature

Binomial nomenclature is the system of giving every organism a scientific name consisting of two parts.

Aims and Principles

1. The first part of the scientific name represents the genus and begins with a capital letter.

2. The second part represents the species name and begins with a lowercase letter.

3. Scientific names are written in italics when printed.

4. When handwritten, both parts are underlined separately.

Local Examples

• Corvus splendens – House crow (Desi Kaak)

• Allium cepa – Onion (Pyaaz)

Importance

Binomial nomenclature eliminates confusion caused by different local and common names. It provides a universal scientific naming system that is understood throughout the world.

11. State the complications of classifying viruses.

Viruses create complications in biological classification because:

1. They are acellular and do not have a cellular structure.

2. They lack independent metabolic machinery.

3. They cannot reproduce independently and require a host cell for reproduction.

4. They do not fit into any of the three domains or five kingdoms.

5. They remain inactive outside a host cell.

Therefore, viruses occupy a position between living and non-living entities, making their classification difficult.

Notes by Sir Dilawar

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