Q1: What is biodiversity?
Ans: The immense variety of living organisms found in countless forms and habitats on the Earth is called biodiversity. It is essential for keeping nature stable and functioning.
Q2: What are endemic species? Give one example.
Ans: Species that are restricted to particular regions of the world and are not found naturally anywhere else are called endemic species. Example: Neelakurinji, found only in India.
Q3: What are biodiversity hotspots?
Ans: Regions that support a large number of endemic species and have undergone significant habitat loss are known as biodiversity hotspots. The Western Ghats and the Himalayas are examples of global biodiversity hotspots.
Q4: What is biological classification?
Ans: The scientific system of grouping living organisms based on their similarities and/or differences in a systematic manner is known as biological classification.
Q5: Name the five kingdoms proposed by Robert H. Whittaker.
Ans: The five kingdoms proposed by Whittaker in 1969 are Monera, Protista, Fungi, Plantae and Animalia.
Q6: What are saprophytes? Give one example.
Ans: Organisms that feed on dead organic matter such as fallen leaves, twigs or dead organisms and break them down into simpler substances are called saprophytes. Most fungi, such as mushrooms, are saprophytes.
Q7: Name the material that makes up the cell wall of fungi.
Ans: The cell wall of fungi is made of chitin.
Q8: Why are bryophytes called the amphibians of the plant kingdom?
Ans: Bryophytes are called the amphibians of the plant kingdom because they can live on land but still require water for reproduction, as male reproductive cells must swim to reach female cells.
Q9: What are rhizoids?
Ans: Rhizoids are root-like structures present in bryophytes. They are not true roots but help the plant anchor itself and absorb water and nutrients from the surroundings.
Q10: Name the two vascular tissues present in pteridophytes.
Ans: Pteridophytes have two vascular tissues – xylem, which transports water, and phloem, which transports food throughout the plant body.
Q11: What does the term ‘gymnosperm’ mean and what is special about their seeds?
Ans: Gymnos means naked and spermos means seed. The seeds of gymnosperms are not enclosed in fruits and are often exposed on cones, as seen in pines.
Q12: What are angiosperms? Give one example.
Ans: Angiosperms are flowering plants whose seeds are enclosed within fruits. They are the most diverse plant group on Earth. Example: Gulmohar.
Q13: On what basis are animals in Kingdom Animalia divided into invertebrates and chordates?
Ans: Animals are divided on the basis of the presence or absence of a notochord, which is a flexible rod-shaped structure. Animals without a notochord are invertebrates and those possessing it are chordates.
Q14: What is the defining structural feature of phylum Arthropoda?
Ans: The defining structural feature of Arthropoda is the development of a hard external skeleton (exoskeleton), which provides protection, reduces water loss and supports powerful muscles.
Q15: Who introduced binomial nomenclature and when?
Ans: Binomial nomenclature was introduced by Carolus Linnaeus in the 18th century. In this system, every organism has a scientific name consisting of two parts – genus and species.
Q16: Write the scientific name of mango and state one rule for writing it.
Ans: The scientific name of mango is Mangifera indica. The genus name begins with a capital letter and the species name is written in lower case; when printed, the name is written in italics.
Q17: Write the correct hierarchical sequence of classification from the broadest to the most specific level.
Ans: Kingdom → Phylum → Class → Order → Family → Genus → Species. At each lower level, organisms share more common features with each other.
Q18: What are fossils and how are they useful to scientists?
Ans: Fossils are the preserved remains of plants and animals found in layers of rocks, sand and mud. They act as natural records that help scientists understand how life has changed over millions of years.
Q19: Into how many groups are vertebrates classified? Name them.
Ans: Vertebrates are classified into five groups – fish, amphibians, reptiles, birds and mammals – based on broad patterns of their habitat use, body covering and reproduction.
Q20: Name any two human activities that threaten biodiversity.
Ans: Pollution and deforestation are two major human activities that reduce biodiversity. When one species disappears due to such activities, other species that depend on it may also eventually disappear.