Unit 2: Biodiversity — Short Questions

Ans The term used for the variety of life on Earth is biodiversity, or biological diversity.

Definition

Biodiversity means the variety of organisms in a particular area including all living things and their interactions. It encompasses the variety of genes, species, ecosystems and functions.

Ans Importance of Biodiversity

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

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

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

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

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

Ans Linnaeus developed a system that went from broadest to most specific. The levels of classification he used are:

Kingdom, Phylum, Class, Order, Family, Genus and Species.

Taxa Lion Corn
Kingdom Animalia Plantae
Phylum Chordata Tracheophyta
Class Mammal Liliopsida
Order Carnivora Poales
Family Felidae Poaceae
Genus Panthera Zea
Species Panthera leo Zea mays

Archaea

i. These are the most primitive organisms on Earth.

ii. They are prokaryotes but their cell wall does not contain peptidoglycan. Their rRNA (ribosomal RNA) is more closely related to eukaryotes than to bacteria.

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

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

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

vi. Major archaebacteria include Methanogens, Halophiles, Thermophiles and Acidophiles.

Bacteria

i. They are the true bacteria. They are unicellular. Many live solitary although some form chains, clusters, or colonies of cells.

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

v. This domain contains kingdom Eubacteria.

vi. Major groups in this kingdom are bacteria and cyanobacteria.

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 wall but possess chitin.

Ans The Kingdom Animalia of eukaryotes includes organisms which are eukaryotic, multicellular heterotrophic and lack cell walls. They develop from embryos. They ingest food and digest it within their bodies.

Ans Kingdom Fungi

i. This kingdom consists of fungi which are eukaryotic, heterotrophic organisms that 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.

Ans Classification into three domains in based on difference in the sequence of nucleotides in the rRNA (ribosomal ribonucleic acid) of the cell, the cell membranes lipid structure and its sensitivity to antibiotics. The three domains are:

i. Domain Archaea

ii. Domain Bacteria

iii. Domain Eukarya

Ans Viruses are not included in any kingdom because they lack any of the characteristics of the three domains of life.

Ans

i. It facilitates by providing a universal naming system for species.

ii. It provides an unambiguous universally recognized way of naming living things via a genus name followed by a more specific species name.

iii. This system provides a standard way of communication, whether the language of a particular biologist is Chinese, Arabic, Spanish, or English.

Ans.

a) Biodiversity

Biodiversity is defined as "the variety of living organisms on i...th."

b) Classification

The grouping of organisms is called classification.

c) Taxonomy

Taxonomy is the branch of biology concerned with identification, naming and classification of organisms.

d) Systematics

The scientific study of diversity of organisms and their evolutionary relationship is called systematic.

e) Domain

In 1990 Carl Woese introduced a three domains system of classification. The three domains of life are Archaea, Bacteria and Eukarya.

f) Taxa

The group into which organisms are classified are known as taxonomic categories or taxa (singular 'taxon'). The taxa form a ladder, called taxonomic heirarchy. There are seven main taxonomic ranks: Kingdom, phylum or division, class, order family, genus and species.

g) Species

Species is a group of similar organisms capable of interbreeding or exchanging genes among themselves and producing fertile offspring.

Ans. Aims of Classification

The main aims and objectives of classification are:

(1) To determine similarities and differences between organism.

(2) To arrange organisms on the basis of similarities and differences.

(3) Identify the organisms to study them systematically.

(4) To find out evolutionary relationship among organisms.

Ans. Definition

Specie is a group of similar individuals capable of interbreeding among themselves and producing fertile offspring.

Explanation

Cross between a male donkey and a female horse produces mule. It is infertile, because of the odd number of chromosomes, they can't reproduce. So, it is not species. Species is the most basic unit of classification, as well as a taxonomic rank.

Ans.

a) Aristotle

The Greek Philosopher Aristotle was the first person who classified the living organisms.

b) Carolus Linnaeus

He grouped species according to similar physical characteristics. According to earlier classification system, organisms were classified into two kingdoms, then three kingdom and then five-kingdom system. He also introduced binomial nomenclature.

c) Carl Woese

In 1990 Carl Woese introduced a three domains system of classification. The three domains of life are:

i) Archaea

ii) Bacteria

iii) Eukarya

Ans.

(a) Bacteria and Protists

Bacteria Protists
(i) Prokaryotic organisms. (i) Eukaryotic organisms
(ii) They are unicellular, (ii) Unicellular or simple multi-
filamentous or colonial and are cellular and mostly aquatic.
relatively simple in structure.
Examples: Bacteria and Examples: Amoeba, Euglena, and
Cyanobacteria Slime molds.

(b) Fungi and Plants

Fungi Plants
(i) Eukaryotic organisms. (i)Eukaryotic organisms.
(ii) Mostly multi-cellular and (ii) Multi-cellular
some fungi are unicellular.
(iii) Fungi may be saprotroph (iii) Plants are autotrophic with
decomposers. chloroplasts containing chlorophyll.
(iv) Fungi have chitin in their (iv) Plants cell wall is made of
cell walls. cellulose.
(v) Fungi have absorptive mode (v) Plants have photosynthetic
of nutrition. mode of nutrition.
(vi) Examples; black bread mold, (vi) Examples; moss, mustard.
yeast, mushroom etc.

(c) Plants and Animals

Plants Animals
(i) Eukaryotic multi-cellular (i) Eukaryotic multi-cellular.
(ii) Autotrophic with chloroplast (ii) Heterotrophic and lack
containing chlorophyll. chlorophyll.
(iii)They have cellulose in cell (iii) Animals lack cell wall.
walls.
(iv) They cannot move. (iv) They can move from place
to place.
(v) Examples; moss, mustard. (v) Examples; (a) Invertebrates
e.g., Insects, star fish.
(b) Vertebrates e.g., fish, frogs.

Ans.

a) Which is the simplest domain?

Archaea domain is the simplest one. This domain is comprised organisms that are prokaryotic or cells without nuclei. They are single celled and reproduce asexually.

b) Which is the complex domain?

Domain Eukarya is the complex one. It consists of all eukaryotic organisms or these with the largest, most complex cells and the most advanced compartmentalization.

c) Are most bacteria harmful?

Most bacteria are harmless, but certain types can make you sick. These bacteria are a type of pathogen. Pathogens are microorganisms that can cause diseases.

d) Which domains can flourish or survive in most adverse conditions?

Archaea can be found in every ecosystem and environment on Earth. They can survive and thrive in extreme environments.

The archaeal cytoplasmic membrane contains unique lipids that cannot easily be degraded, are temperature and mechanically resistant and highly salt tolerant.

Ans.

(a) Autotrophs

The organisms that are capable of producing their own food are called autotrophs (photosynthetic mode of nutrition) e.g., green plants, cyanobacteria, and algae.

(b) Heterotrophs

Organisms which eat other things as food are called heterotrophs (ingestive mode of nutrition) e.g., animals, animal like protists, etc.

(c) Saprotrophs

The organisms that depend on dead, decaying matter are called saprotrophs (absorptive mode of nutrition) e.g., fungi, bacteria. These are decomposers.

Ans.

Prokaryotes

The organisms which lack nucleus in their cells are called prokaryotes e.g. bacteria.

Eukaryotes

The organisms which have true nucleus in their cells e.g. plant cells.

Ans. Euglena belongs to kingdom Protista.

Reason for Placement

It is a unicellular organism. Euglena has both plant-like (presence of chlorophyll) and animal-like (heterotrophic mode of nutrition in darkness and lack of cell wall) characters. Due to this it is placed in the kingdom Protista.

Characteristics

i) Kingdom Protista includes eukaryotic organisms with a unicellular or simple multicellular structure.

ii) Most organisms belonging to this kingdom are aquatic.

iii) It includes animal like protists called protozoa e.g., Amoeba, Plant like protists called algae e.g., Euglena. Fungi like protists e.g., slime molds.

Ans. In biology, a domain means the largest of all groups in the classification of life. Domain is group of kingdoms or taxonomic category above the kingdom. The three domains of life are Archaea, Bacteria and Eukarya.

Ans. Basis of Three Domain System

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.

Two Kingdom Classification System

(i) It includes two Kingdoms: Plantae and Animalia.

(ii) Bacteria and Cyanobacteria were placed in plant kingdom.

(iii) Unicellular or simple multicellular eukaryotes wrongly placed in kingdom Plantae and Animalia.

(iv) Fungi are wrongly placed in kingdom plantae.

Three Kingdom Classification System

i) It includes three kingdoms: Plantae, Animalia, Protista.

ii) Euglena was placed in kingdom Protista.

iii) Multicellular microscopic organisms were separated from unicellular microscopic organisms.

iv) Fungi were placed in kingdom Plantae.

Five Kingdom Classification System

(i) It includes five kingdoms: Monera, Protista, Fungi, Plantae and Animals.

(ii) Bacteria and cyanobacteria are placed in kingdom Monera.

(iii) Unicellular or simple multicellular eukaryotes placed in kingdom Protista.

(iv) Fungi are placed in kingdom Fungi.

Ans.

i) The Domain Archaea

The domain Archaea have the following characteristics:

a. Archaea are prokaryotic cells.

b. The cell walls of Archaea contain no peptidoglycan.

c. The rRNA (ribosomal RNA) are not found in Bacteria and Eukarya.

ii) The Domain Bacteria

a. Bacteria are prokaryotic cells.

b. The cell walls of bacteria contain peptidoglycan.

c. They contain rRNA that is unique to bacteria.

iii) The Domain Eukarya

a) Eukarya have eukaryotic cells.

b) Not all Eukarya have cells with a cell wall. Their cell wall contains no peptidoglycan.

c) Eukarya contains rRNA that is unique to Eukarya.

Ans. Binomial nomenclature is the method of giving scientific names to living organisms. Since each name has two parts so it is called binomial nomenclature e.g., biological name of human being is Homo sapiens. Our genus name is homo and species name is sapiens.

Ans The placement of an organism in the wrong taxonomic group can cause big problems for conservation and scientific studies. For conservation, it might lead to protecting the wrong species or mismanaging habitats, which can harm ecosystems and biodiversity. It can also affect areas like agriculture and medicine, where knowing the right species is crucial for discoveries. Additionally, misclassifying invasive species or misunderstanding an organism's role in the food web can disrupt ecosystems. Overall, accurate classification is essential for effective conservation, reliable research, and maintaining ecological balance.

Ans The following steps would be taken to name and classify the new organism:

1. Study the organism's characteristics (structure, function, and behaviour) to identify its unique features.

2. Compare that new organism with existing organisms to determine its taxonomic group.

3. Place it in the correct Kingdom, Phylum, Class, Order, Family, Genus, and Species.

4. Assign the scientific name to that organism according to the rules of binomial nomenclature; the first name would represent its genus and must be capitalized, while the second name would represent the species and will be written in lower case.

5. Publish these findings in a scientific journal for validation.