9th Class Biology Unit 2 Biodiversity Long Questions

1.Discuss the concept of biodiversity and its significance in maintaining the health of ecosystems.

Ans Definition
Biodiversity means the variety of organisms in a particular area

Explanation / Dependence and Distribution of Biodiversity
Biologists have named and classified almost 2 million kinds of organisms. Biodiversity is not evenly spread out. The biodiversity in a place depends on factors like climate, altitude, and soil type. Tropical regions have more biodiversity than polar regions.

Importance of Biodiversity
Biodiversity provides many essential services for humans and the planet. Here are some key benefits of biodiversity.

i. Ecosystem Stability: Biodiversity helps maintain the balance of ecosystems by contributing to the biogeochemical cycle such as water cycle, carbon cycle, and nitrogen cycle.

ii. Climate Regulation: Plants and algae absorb carbon dioxide, helping to regulate the climate.

iii. Natural Resources: Biodiversity provides a vast array of resources, from food and medicine to building materials and fuel.

iv. Economic Benefits: Biodiversity supports numerous industries, including agriculture, tourism, and pharmaceuticals.

International Biodiversity Day
The united nations has designated May 22nd as International Biodiversity Day. It is celebrated to promote the protection of biodiversity.

2.What is classification? Describe the aims and basis of classification.

Ans. Known Number of Animals and Plants Species
Biologists have identified and described about 02 million kinds of organisms. Out of these, 0.5 million are the kinds of plants and 1.5 million are the kinds of animals. It is only a small percentage of the total kinds, which live on Earth. Every year, biologists discover thousands of new kinds of organisms. They are challenged to organize their knowledge of such diversity.

Need of Classification
To study such a large collection of organisms, biologists classify them.

Definition
Classification is a method by which biologists divide organisms into groups and sub-groups on the basis of similarities found in them.

Aims and Principles of Classification
The main aims of classification are;
a. To determine similarities and differences among organisms so that they can be studied easily.
b. To find the evolutionary relationships among organisms.

Basis of Classification
i. Physical Characteristics
Biologists classify organisms into groups and subgroups on the basis of similar physical characteristics.

ii. Genetics
In recent times, they also take help from genetics. They find the genetic similarities and differences among organisms. Then they use this information to know similarities and differences in their structures and functions.

Advantages of Classification
• Classification allows biologists to group similar organisms together, making it easier to identify and understand their characteristics, relationships, and evolutionary history. It helps us understand the vast diversity of living organisms on Earth.

• Classification provides a framework for studying and comparing different species.

• It explains the inter-relationship amongst various organisms.

• It helps in the identification of new species and in understanding their evolutionary relationships.

• Classification provides a common language for biologists around the world, enabling effective communication in the study of organisms.

Overall, classification is crucial for our understanding of the natural world and for the conservation and management of biological diversity.

3.Describe taxa or taxonomic ranks of taxonomy orderly. / Explain taxonomic hierarchy.

Ans. Definition
The groups into which organisms are classified are known as taxonomic ranks or taxa (singular "taxon").

Linnaean System of Taxonomic Ranks
The Swedish botanist Carl Linnaeus devised the Linnaean system of taxonomic ranks in 1735. In this system, Linnaeus suggested seven taxonomic ranks i.e., kingdom, phylum (division), class, order, family, genus and species. In 1977, the rank of domain was added to this system. The taxonomic ranks are defined as below:

Taxonomic Ranks
Domain: The highest taxonomic rank is domain. All organisms are divided into three domains: Bacteria, Archaea, and Eukarya.

Kingdom Domain is further divided into kingdoms. For example, the domain Eukarya is divided into four kingdoms i.e., Animalia, Plantae, Fungi, Protista.

Phylum (Division for plants and fungi): Each kingdom is subdivided into related phyla or divisions.

Class Each phylum/division is divided into related classes.

Order Each class is further divided into related orders.

Family Each order is broken down into related families.

Genus Each family is divided into related genera (singular genus).

Species It is the most specific level of classification. A species consists of similar organisms that can interbreed and produce fertile offspring.

Table 2.1 Classification of fruit fly, human and pea

4.Define Species. Give two exceptions for the species concept.

Ans Species the Basic Unit of Classification
A species is a group of organisms which can interbreed freely among them and produce fertile offspring but are reproductively isolated from all other such groups in nature". Each species has its own distinct structural, ecological and behavioural characteristics.

Two Exceptions for the Species Concept

(i) Artificial Cross Breeding
In the definition of species we must emphasize "in nature" because two organisms related to two different but closely related species can cross breed under artificial conditions. In such unnatural crosses, they produce infertile offspring. A cross between a male donkey and a female horse produces an infertile offspring, the mule.

(ii) Organisms with Asexual Reproduction
The criteria of interbreeding cannot be used for species recognition in organisms who reproduce asexually and don't interbreed with one another e.g. many unicellular.

5.Give an account of history of classification.

Ans History of Classification
The history of the classification system can be traced back to ancient times.

Aristotle and Ibn Rushd
i. The Greek philosopher Aristotle (384-322 BC) was the first who classified organisms into two groups i.e., plants and animals.

ii. In 1172 Ibn Rushd (Averroes) translated Aristotle's book "de Anima (On the Soul)" into Arabic.

Abu Usman Umer Al-Jahiz
The Arab scholar Abu Usman Umer Al-Jahiz (781-869 AD) described the characteristics of 350 species of animals. He wrote a lot about the life of ants.

Andrea Caesalpinia
The Italian botanist Andrea Caesalpinia (1519-1603 AD) divided plants into fifteen groups and called them genera.

Tournefort
The French botanist Tournefort (1656-1708 AD) introduced the taxa of class and species.

Carl Linnaeus
The Swedish biologist Carl Linnaeus (1707-1778 AD) created a taxonomic hierarchy of organisms with six taxa i.e., Kingdom, Class, Order, Family, Genus, and Species.

Classification Systems

a. Two-Kingdom Classification System
Introduction
It was the earliest classification system in which all organisms were classified into two kingdoms i.e., Plantae and Animalia.

Kingdom Plantae
The organisms that make their own food (autotrophs) were classified in the kingdom plantae.

Kingdom Animalia
On the other hand, the organisms that cannot make their own food (heterotrophs) were classified in kingdom animalia. According to two kingdom system, prokaryotes (bacteria, archaea) and fungi were members of kingdom plantae.

Drawbacks / Shortcomings
i. Some taxonomists found this system unworkable because many unicellular organisms like Euglena have both plant-like (presence of chlorophyll) and animal-like (heterotrophic mode of nutrition in darkness and lack of cell wall) characteristics. So, a separate kingdom was proposed for such organisms.

ii. This system also did not clear the difference between prokaryotes (bacteria and archaea) and eukaryotes.

b. Three-Kingdom Classification System
Introduction
In 1866, the German zoologist Ernst Hackel proposed a third kingdom i.e., Protista for Euglena-like organisms. He also included prokaryotes (bacteria and archaea) in the kingdom Protista. In this system, fungi were still included in the kingdom Plantae.

Drawbacks / Shortcomings
i. Some taxonomists disagreed about the position of fungi in kingdom Plantae.

ii. Fungi resemble plants in many ways but are heterotrophs which get their food by absorption.

iii. They do not have cellulose in their cell walls but possess chitin.

c. Five Kingdom Classification System
E-Chatton
In 1937, French biologist E-Chatton suggested the terms, "Procariotique" to describe bacteria and "Eucariotique" to describe protusta, fungi, animal and plant cells.

Robert Whittaker
In 1967, American ecologist Robert Whittaker introduced the five-kingdom classification system.

Basis of Five Kingdoms System
This system is based on;
i. The levels of cellular organization i.e prokaryotic (bacteria, archaea), unicellular eukaryotic (Protista) and multicellular eukaryotic (fungi, plants and animals).

ii. The modes of nutrition i.e. photosynthesis, absorption, and ingestion.

Five Kingdoms
On this basis, organisms were classified into five kingdoms: Monera, Protista, Fungi, Plantae and Animalia.

Margulis and Schwartz
In 1988, American biologists Margulis and Schwartz modified the five-kingdom classification of Whittaker. They considered genetics along with cellular organization and mode of nutrition in classification. They classified the organisms into the same five kingdoms as proposed by Whittaker.

d. Three-Domain Classification System
Carl Woese
In 1977, American microbiologist Carl Woese (1928-2012 AD) added a level of classification (the domains) above the kingdoms present in the previously used five-kingdom system.

Three Domains
He classified the organisms into three domains i.e. Archaea, Bacteria and Eukarya. It was actually a division of the prokaryotes in two domains (Archaea and Bacteria). While all eukaryotes were placed in a single domain i.e., Eukarya.

Basis of Classification
This classification is based on the differences between Archaea and Bacteria.

6.Describe the domains of living organisms. / Compare and (contrast) the domains of Archaea and Eubacteria focusing on their Key characteristics.

Ans Classification into three domains is based on difference in the sequence of nucleotides in the rRNA (ribosomal Ribonucleic acid) of the cell, the cell membrane lipid structure and its sensitivity to antibiotics.

1. Domain Archaea
i. These are the most primitive organisms on Earth.

ii. They are prokaryotes but their cell wall does not contain peptidoglycan.

iii. Their rRNA (ribosomal RNA) is more closely related to eukaryotes than to bacteria.

iv. Their cell membrane contains unique lipids which enable them to live in extreme environments e.g., hot springs, salt lakes, deep-sea hydrothermal vents, and acidic or alkaline waters.

v. However, they also exist in more common environments like soil and oceans.

vi. Some archaea obtain energy from inorganic compounds such as sulphur or ammonia. Other groups perform photosynthesis but do not produce oxygen.

vii. The domain Archaea contains kingdom Archaebacteria (ancient bacteria).

viii. Major archaebacteria include Methanogens (produce methane as byproduct), Halophiles (found in extremely salty environments), Thermophiles (found in hot springs), Acidophiles (found in extremely acidic environments).

2. Domain Bacteria
i. They are the true bacteria.

ii. They are also prokaryotic and have cell wall made of peptidoglycan.

iii. Bacteria are found everywhere including soil, water, air, and living organisms.

iv. They are unicellular. Many live solitary although some form chains, clusters, or colonies of cells.

v. Most are heterotrophic but some perform photosynthesis because they have chlorophyll.

vi. This domain contains kingdom Eubacteria.

vii. Major groups in this kingdom are bacteria and cyanobacteria. Some bacteria cause diseases and many play essential roles in nutrient recycling.

3. Domain Eukarya
i. Eukarya consists of kingdoms protista, fungi, plantae and animalia.

ii. It includes all eukaryotes which consist of complex, eukaryotic cells containing nucleus and other membrane-bound organelles.

7.Describe the diagnostic classification of the four Kingdoms within the domain Eukarya.

Q.7. Describe the diagnostic classification of the four Kingdoms within the domain Eukarya.

Domain Eukarya
The domain Eukarya is further classified into four Kingdoms

1. Kingdom Protista
i. Kingdom Protista includes eukaryote which are unicellular or colonial or filamentous or simple multicellular. Simple multicellular means that they do not have multicellular sex organs.

ii. There are three types of protists.

(a) Plant-like protists have cell walls made of cellulose. They have chlorophyll in chloroplasts and are autotrophs. They are called algae (e.g., Euglena, diatoms).

(b) Animal-like protists are heterotrophs and ingest food. They have no cell wall. They are called protozoas (e.g., g. Amoeba, Paramecium).

Fungus-like protists produce hyphae-like structure and are saprophytic e.g., slime molds and water molds.

(c) Certain protists are parasitic and cause diseases e.g., Plasmodium causes malaria, Entamoeba histolytica causes amoebic dysentery, and Trypanosoma causes sleeping sickness.

2. Kingdom Fungi
i. This kingdom consists of fungi which are eukaryotic, heterotrophic organisms and are unicellular or multicellular.

ii. Their cells are covered by cell wall made of chitin (a polysaccharide).

iii. Fungi get nutrients in a unique way. They do not ingest food like animals and some protists. They absorb food from surroundings.

iv. Examples are mushrooms, rusts, smuts and molds.

v. Some fungi are used in the production of bread, cheese and beer. Others have medicinal properties, such as penicillin, an antibiotic derived from the fungus Penicillium.

3. Kingdom Plantae
i. It includes plants which are eukaryotic, multicellular organisms with cell walls made of cellulose.

ii. They are autotrophic and prepare food through photosynthesis.

iii. All plants develop from embryos.

iv. Examples are mosses, ferns, conifers and flowering plants.

4. Kingdom Animalia
i. This kingdom of eukaryotes includes animals which are eukaryotic, multicellular and heterotrophic.

ii. They develop from embryos.

iii. They ingest food and digest it within their bodies.

8.Describe the Challenges of classifying viruses within the traditional three domains of life.

Ans Challenges of Classifying Viruses
Following are the challenges of classifying viruses within the traditional three domain of life:

i. Viruses typically lack many of the genes that are universal at among the three domains of cellular life in particular genes for translation system components.

ii. However, a small core of viral "hall mark genes" have been discovered that are missing in cellular life forms.

iii. Viruses lack any of the characteristics of the three realms of life.

Status of Viruses in Classification

(a) Viruses are ultramicroscopic creatures that are at the borderline of living and non-living.

(b) They are acellular i.e., they are not made of cells and do not have organelles.

(c) A virus consists of nucleic acid (DNA or RNA) surrounded by a protein coat.

(d) They cannot run any metabolism and depend upon the host cell (including plants, animals, and bacteria) to replicate and synthesize their proteins.

(e) Because they lack any of the characteristics of the three domains of life, viruses are not included in those categories.

9.Describe briefly about prions and viroids.

Ans i. Prions and viroids are also acellular particles and are also not included in classification system.

ii. Prions are composed of proteins only and viroids are composed of circular RNA only.

iii. Both these particles cause infectious diseases in certain plants.

10.Write a note on coronavirus.

Ans Introduction
Coronavirus is a virus, identified in late 2019 in Wuhan, China. It caused a pandemic of respiratory illness, called COVID-19.

Spreading
i. The virus primarily spreads through respiratory droplets when an infected person coughs, sneezes, talks, or breathes.

ii. It can also spread by touching surfaces contaminated with the virus.

Symptoms
Common symptoms of this disease include fever, cough, shortness of breath, fatigue, body aches, loss of taste or smell, sore throat, and headache. In some cases, it can lead to severe respiratory problems, especially in older adults and people with underlying health conditions.

Prevention
i. Wearing a mask over nose and mouth can help prevent the spread of disease.

ii. Washing hands frequently with soap for at least 20 seconds or use hand sanitizer with at least 60% alcohol can also prevent the spread of disease.

iii. Vaccination plays a crucial role, in protecting from COVID-19. Vaccines help immune system recognize and fight the virus, reducing the severity of the disease.

11.Explain rules and guildlines for suggesting scientific names to organisms. / What is binomial nomenclature? Describe aims, principles and importance of binomial nomenclature using local examples.

Ans Introduction
The great Swedish naturalist Carolus Linnaeus was the founder of the scientific naming system of organisms. The scientific name of an organism consists of two parts. The first part is the name of the genus to which the organism belongs. The second part is the name of the species. The system of scientific naming of organisms is termed as binomial nomenclature.

Significance of Binomial Nomenclature

i. Same Names
In binomial nomenclature, two organisms cannot have the same name.

ii. Scientific Names from Latin Language
The words of scientific name are taken from Latin language (spoken by no country) so that no country is favoured. The scientific name of an organism is the same anywhere in the world. This system provides a standard way of communication, whether the language of a particular biologist is Chinese, Arabic, Spanish, or English.

iii. Different Names for the Same Organisms
Various regions have different names for the same organism e.g. the common name of onion in Urdu is 'Piyaz' but in different regions of Pakistan it is also known as 'ganda' or 'bassal' or 'vassal'. In other countries it has other sets of names.

iv. Common Names
In some cases, several different organisms are called by the same common name, e.g. 'blue bell' is used for dozens of plants with bell shaped flowers. Similarly, 'black bird' is used for crow as well as for raven.

v. No Scientific Basis for Common Names
Common names have no scientific basis. For example; a fish is a vertebrate animal with a backbone, fins and gills. But several common names of 'silver fish', 'cray fish', 'jell fish', and 'star fish' do not fit to the true definition of fish.

Rules of Binomial Nomenclature
The scientific naming of an organism is done in accordance with some international rules. Some important rules of binomial nomenclature are:

1. For scientific naming, words are taken from Latin language.

2. Every scientific name has two parts. The genus name always comes first followed by the species name.

3. Every scientific name should have to be unique because the same name cannot be used for naming two different organisms.

4. The first part of the name i.e. genus name should begin with a capital letter. The second part of the name i.e. species name should begin with small letter.

5. At the time of printing of a scientific name, it should be typed in Italics.

6. When a scientific name would be hand written, two parts of it should be separately underlined.

Unit 2: Biodiversity — Long Questions