BIOLOGICAL CLASSIFICATION
QUESTION ANSWER
The five kingdoms are as follows:
Ques: How is the
five-kingdom classification more advantageous than the two-kingdom
classification?
Ans: The five-kingdom classification is based on
the following criteria:
- The structure of the cell
- The structure of the body
- The mode of nutrition
- The kind of reproduction and
- Phylogenetic relationships
among different organisms and kingdoms.
The two-kingdom
classification is based simply on plants and animals.
Ques: Who proposed the
five-kingdom classification?
Ans: RH Whittaker proposed the five-kingdom
classification. The five kingdom classification includes Monera, Protista,
Fungi, Plantae and Animalia.
Ques: What are the
similarities between virus particles and non-living objects?
Ans: Virus particles are
intermediate between living and non-living things. They behave like living
things inside their hosts and like non-living crystals outside their host
cells. They resemble non-living things in the following aspects:
- Inert nature without living
activities.
- They cannot reproduce
themselves.
Ques: Mention the main
difference between a virus and a viroid?
Ans: A virus contains protein coal called the
capsid and a core containing the genetic material. That genetic material may be
either DNA or RNA. But, the viroid contains only genetic material, but a
protein coat.
Ques: What are the
eukaryotic kingdoms of the five-kingdom classification proposed by RH
Whittaker?
Ans: The organisms with cells containing a
true nucleus are called eukaryotic organisms. The four eukaryotic kingdoms in the
five-kingdom classification include Protista, Fungi, Plantae, and Animalia.
Ques: State whether
the chemosynthetic bacteria are autotrophic or heterotrophic?
Ans: The chemosynthetic bacteria are autotrophic because
they prepare their own food.
Ques: What are the
economic uses of archaebacteria and heterotrophic bacteria?
Ans: Archaebacteria converts milk into curd and cheese and
produces methane gas in biogas plants. Heterotrophic Bacteria improve the
fertility of the soil by nitrogen fixation, ammonification and nitrification. Example: Rhizobium
bacteria.
Ques: How can a farmer
improve his crop yield by using cyanobacteria in his agricultural fields?
Ans: Blue-green algae that belong to the
kingdom monera are also called cyanobacteria.
They have the ability to fix atmospheric nitrogen due to the presence of
heterocysts. After the death and decay of their filaments, a lot of
nitrate-nitrogen is mixed up with the soil. Crop plants can absorb this nitrate
nitrogen, grow vigorously, and produce more grains.
Short Answer Type Questions (2 Marks)
Ques: Why are both
autotrophic cyanobacteria and heterotrophic bacteria classified under
eubacteria of the kingdom Monera?
Ans: The similar features of autotrophic
cyanobacteria and heterotrophic bacteria are as follows:
- They do not have a true nucleus
with a nuclear membrane.
- DNA is directly present in
the cytoplasm without a protein coat.
- All the ribosomes are of the 70S type.
- All the membranous organelles
are absent.
Ques: Why is
Trypanosoma included in the kingdom Protista?
Ans: Trypanosoma is a unicellular organism.
It consists of a true nucleus with a nuclear membrane. It also consists of
membranous organelles. So, it is a unicellular eukaryote. All unicellular
eukaryotic organisms are included in the kingdom Protista. The other features
of Trypanosoma are the presence of nuclear endosomes, granular food particles,
and binary fission.
Ques: Why is
Neurospora extensively used in genetic experiments?
Ans: Neurospora is used in genetic
experiments for three reasons.
(1) It can easily be
grown in a nutrient medium containing simple organic substances, mineral
salts, vitamins, and hormones in the lab.
(2) Its life cycle is
very short.
(3) It is very easy to
introduce mutations in Neurospora by using X-rays.
Ques: Define the terms
‘phycobiont’ and ‘mycobiont’?
Ans: Lichens consist
of a permanent association between an alga and a fungus. The algal component is
called phycobiont, and the fungal component is mycobiont. In this permanent
symbiosis, the fungus mycelium absorbs and supplies water and mineral nutrients
to the alga. The alga prepares food by photosynthesis and supplies it to the
fungus.
Ques: Why are some flowering plants
parasitic?
Ans: Some plants become parasitic to absorb water, minerals, foot
materials from other plants, as they do not have chlorophyll to manufacture food.
Cuscuta, Cassytha, Orobanche, Loranthus, and Striga are parasitic plants.
Ques: Why do polluted water bodies show more numbers of Nostoc
and Oscillatoria under the microscope?
Ans: A water body suddenly turns green due to the rapid growth of
algae. This is called an algal bloom. If you collect that water
and observe it under the microscope, you can find a number of
algal species including Nostoc and Oscillatoria.
Long Answer
Questions (3 Marks)
Ques: What is Taxonomy? What is its scope?
Ans: The branch of science that deals with the nomenclature,
identification, description, and classification of both living and extinct
organisms are called taxonomy. The
living organisms include bacteria, fungi, non-flowering plants, flowering
plants, protozoans, helminth worms, annelids, arthropods, molluscs, echinoderms, and vertebrates. It is
based on the external features, internal features, and phylogenetic
relationships of organisms. The organisms are classified into different taxa or
levels like Kingdom, Phylum, Division, Class, Order, Family, Genus and Species.
Ques: What are ‘pearls of the ocean’? What are their deposits?
Ans: Diatoms are nicknamed “pearls of the ocean”. They are
so-called because of the ornamentations on their cell walls. The siliceous cell walls
of diatoms are called the frustules.
They are the chief autotrophs in the surface waters of oceans.
After death,
diatom cells reach the bottom of the ocean and accumulate there for billions of
years. These deposits are for the diatomaceous earth. It has a number of
applications in different industries.
Ques: How are fungi useful in our daily lives?
Ans: Saprophytic fungi keep the earth and our surroundings clean
by decomposing dead plants and animals. Fungal mycelium binds the soil
particles together and improves the soil structure. Some fungi can be used in
the biological control of pests and diseases. Edible mushrooms are rich in
proteins and vitamins. Some fungi are cultured in labs to produce useful
organic acids. Yeast is used in the bakery industry and also in the fermentation
of carbohydrates into alcohol.
Ques: How are ‘fairy
rings’ formed on the forest floor after heavy rains?
Ans: Soil consists of a thick mat for the
mycelium of mushrooms. After heavy rains, nutrients in the soil get dissolved
in soil moisture and are easily absorbed by mycelia. The mycelia grow in such a
way that the central part gets exhausted and the peripheral part grows in
diameter. The mycelia produce a ring of fruiting bodies called basidiocarps.
They appear like fairy rings.
Ques: What are
insectivorous and parasitic plants? Give some examples
Ans: The insect-eating plants are
called insectivorous plants. They live in soils that are
deficient in nitrogen, So, they depend on insects for available nitrogen. They are butterworts, pitcher plants, sundews,
and venus flytrap. Plants that depend on other plants for water, minerals, and food are called parasitic plants. The roots
of parasitic plants are called haustoria. Some of the parasitic plants are
dodder, Orobanche, Loranthus, Striga.
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