Classification of Plants and Energy Flow in Ecosystems

A comprehensive set of practice questions covering plant classification (Kingdom Plantae), ecosystem energy dynamics, and bio-geo-chemical cycles including Carbon, Oxygen, and Nitrogen cycles.

What are 'Phanerogams'?

Flowering plants that have special structures for reproduction and produce seeds are called Phanerogams; these seeds contain stored food and an embryo used during germination.

On what basis are plants classified at the primitive level?

The primitive level of plant classification begins with morphology, specifically the presence or absence of organs.

How are Phanerogams further classified based on seed enclosure?

They are classified into Gymnosperms (seeds not enclosed in a fruit/naked) and Angiosperms (seeds enclosed in a fruit).

Why is the Division Bryophyta called the 'amphibians' of the plant kingdom?

They are called amphibians because they grow in moist soil but require water for the process of reproduction.

What are the physical characteristics of Bryophytes?

They are thalloid, multicellular, and autotrophic; their body is flat and ribbon-like without true roots, stems, or leaves, instead possessing root-like rhizoids and leaf-like parts.

What are the two sub-kingdoms of Kingdom Plantae according to Eichler ($1883$)?

The two sub-kingdoms are Cryptogams and Phanerogams.

What characterizes the Division Thallophyta (Algae)?

These plants grow mainly in water, lack specific parts like roots or stems, and are autotrophic due to the presence of chlorophyll; they usually have a soft, fibre-like body.

What is a unique cellular characteristic of Spirogyra?

Spirogyra has spirally arranged ribbon-like chloroplasts within its cells.

What is the primary mode of reproduction and physical trait of Division Pteridophyta?

They have well-developed roots, stems, and leaves with separate conducting tissues, but they do not bear flowers or fruits; they reproduce asexually via spores formed on the posterior surface of leaves.

What are 'Gymnosperms'?

Gymnosperms are mostly evergreen, perennial, and woody plants with unbranched stems; they bear male and female flowers on different sporophylls of the same plant and have seeds without natural coverings.

What is the difference between monocotyledonous and dicotyledonous plants regarding their seeds?

Dicotyledonous seeds can be divided into two equal halves (two cotyledons), whereas monocotyledonous seeds cannot be divided (single cotyledon).

Compare the root systems of Dicot and Monocot plants.

Dicot plants have well-developed primary tap roots, while monocot plants have fibrous roots.

What is a 'Trophic level' in a food chain?

A trophic level is the step at which an organism obtains its food in the chain; the amount of matter and energy decreases from producers at the lowest level to top consumers at the highest level.

What is the 'Eltonian Pyramid'?

It is the Ecological Pyramid first proposed by British scientist Charles Elton in $1927$ after studying the Tundra Ecosystem.

Why is the flow of energy in an ecosystem considered 'one way' transport?

Energy from the sun is stored by plants and passed through trophic levels, but since no part of the energy ever returns to the sun, the passage is unidirectional.

What is the 'Bio-geo-chemical cycle'?

The cyclical flow of nutrients within an ecosystem, where nutrients are continuously transferred between abiotic and biotic factors, is called the bio-geo-chemical cycle.

What is the difference between Gaseous and Sedimentary cycles?

Gaseous cycles accumulate abiotic nutrient materials in the atmosphere (e.g., Nitrogen, Oxygen), while Sedimentary cycles accumulate materials in soil and rock (e.g., Iron, Calcium, Phosphorus).

What are the four main processes of the Nitrogen cycle?

$1$) Nitrogen fixation, $2$) Ammonification, $3$) Nitrification (ammonia to nitrite and then nitrate), and $4$) Denitrification (conversion of nitrogen compounds into gaseous nitrogen).

What are the main biotic processes of the Carbon cycle?

Photosynthesis ($6 CO_{2} + 12 H_{2}O \rightarrow C_{6}H_{12}O_{6} + 6 O_{2} + 6 H_{2}O$) and Respiration ($C_{6}H_{12}O_{6} + 6 O_{2} \rightarrow 6 CO_{2} + 6 H_{2}O + \text{Energy}$).

How much of the atmosphere is composed of Oxygen and Nitrogen?

Oxygen forms $21\%$ and Nitrogen forms $78\%$ of the atmosphere.

What are 'Sori' in fern plants?

Sori are groups of sporangia arranged along the back of the leaf margin that produce spores for asexual reproduction.

What is the distinction between 'Aerobes' and 'Anaerobes'?

Aerobes are micro-organisms that use oxygen for respiration, while anaerobes are microbes that do not need oxygen.