30 short answer questions for Class 11 Biology students on Unit I: Diversity of Living Organisms, designed for 2-3 marks each.
Unit I: Diversity of Living Organisms
Instructions: Answer the following questions precisely. Each question carries 2-3 marks.
1.Question: Differentiate between growth and development as characteristics of living organisms.
Answer: Growth refers to an irreversible increase in mass and size of an organism. Development encompasses all the changes an organism undergoes during its lifespan, from conception to death, including growth, differentiation, and maturation.
2.Question: What is taxonomy? Mention its two main components.
Answer: Taxonomy is the branch of biology concerned with the classification, naming, and identification of organisms. Its two main components are nomenclature (naming) and classification (grouping based on similarities).
3.Question: Define biodiversity. Why is it important to conserve biodiversity?
Answer: Biodiversity refers to the variety of life forms on Earth, including the variety of genes, species, and ecosystems. It's important to conserve biodiversity because it provides ecosystem services (e.g., pollination, water purification), genetic resources for human use, and aesthetic/cultural value.
4.Question: Explain the concept of 'binomial nomenclature' with an example.
Answer: Binomial nomenclature is a system of naming organisms where each species is given a two-part scientific name: the first part is the genus name, and the second part is the specific epithet. For example, Homo sapiens for humans.
5.Question: List the five kingdoms of classification proposed by R.H. Whittaker.
Answer: The five kingdoms are Monera, Protista, Fungi, Plantae, and Animalia.
6.Question: What are the key features used to classify organisms into the Kingdom Monera?
Answer: Monerans are prokaryotic, unicellular organisms lacking a true nucleus and membrane-bound organelles. They are typically autotrophic (chemosynthetic or photosynthetic) or heterotrophic.
7.Question: Give two examples of organisms belonging to Kingdom Protista and mention one characteristic feature of the kingdom.
Answer: Examples: Amoeba, Paramecium. Characteristic feature: Protists are eukaryotic, mostly unicellular organisms, and can be autotrophic or heterotrophic.
8.Question: How do fungi obtain their nutrition? Name one parasitic fungus.
Answer: Fungi are heterotrophic and obtain nutrition primarily by absorbing dissolved organic molecules from their environment (saprophytic) or by living on other organisms (parasitic). Example of parasitic fungus: Puccinia (causes rust in plants).
9.Question: Distinguish between algae and fungi based on their cell wall composition.
Answer: Algae typically have cell walls made of cellulose, while fungi have cell walls primarily composed of chitin.
10.Question: What is a herbarium? How is it useful for biological studies?
Answer: A herbarium is a collection of preserved plant specimens, typically dried, pressed, and mounted on sheets. It serves as a ready reference system in taxonomic studies, providing information on plant distribution, morphology, and identification.
11.Question: What are the major characteristics of Kingdom Plantae?
Answer: Plants are eukaryotic, multicellular, and primarily autotrophic (photosynthetic) organisms. Their cells have cell walls made of cellulose, and they show alternation of generations.
12.Question: Name the four major groups of plants in increasing order of complexity.
Answer: Algae, Bryophytes, Pteridophytes, Gymnosperms, Angiosperms. (Note: Some classifications might exclude algae from true 'plant' groups, but for Class 11, it's often included in the context of plant evolution).
13.Question: Why are bryophytes called the "amphibians of the plant kingdom"?
Answer: Bryophytes require water for fertilization, specifically for the movement of their motile male gametes. This dependence on water for reproduction, despite living on land, earns them the title of "amphibians of the plant kingdom."
14. Question: What are the characteristic features of pteridophytes?
Answer: Pteridophytes are the first terrestrial plants to possess true roots, stems, and leaves, and a well-differentiated vascular tissue (xylem and phloem). They reproduce by spores.
15. Question: Differentiate between gymnosperms and angiosperms based on their seeds.
Answer: Gymnosperms have "naked" seeds, meaning their ovules are not enclosed by an ovary wall and remain exposed both before and after fertilization. Angiosperms have seeds enclosed within fruits.
16. Question: What is the significance of flowers in angiosperms?
Answer: Flowers are the reproductive structures of angiosperms. They attract pollinators, facilitate sexual reproduction, and are the site of seed and fruit development.
17. Question: List any three distinguishing features of Kingdom Animalia.
Answer: Animals are eukaryotic, multicellular, and heterotrophic organisms. They lack cell walls, exhibit locomotion, and typically have a definite growth pattern.
18.Question: What is a 'true coelom'? Which phylum was the first to exhibit a true coelom?
Answer: A true coelom is a body cavity that is lined by mesoderm on all sides. The phylum Annelida was the first to exhibit a true coelom.
19. Question: Differentiate between radial symmetry and bilateral symmetry with an example for each. Answer: Radial symmetry means the body can be divided into two identical halves by any plane passing through the central axis (e.g., Cnidarians like jellyfish). Bilateral symmetry means the body can be divided into two identical left and right halves by only one plane (e.g., humans, insects).
20. Question: What is the significance of segmentation in annelids?
Answer: Segmentation allows for specialization of body regions, provides flexibility, and redundancy, meaning if one segment is damaged, others can still function.
21. Question: Name two distinguishing features of the phylum Arthropoda.
Answer: Arthropods have a chitinous exoskeleton and jointed appendages.
22. Question: What is the unique feature of the phylum Echinodermata regarding their skeleton?
Answer: Echinoderms possess an endoskeleton of calcareous ossicles (spines or plates) and a water vascular system.
23. Question: List any three characteristics of the phylum Chordata.
Answer: Chordates possess a notochord, a dorsal hollow nerve cord, and paired pharyngeal gill slits at some stage of their life.
24.Question: What is the function of the notochord in chordates?
Answer: The notochord provides skeletal support and serves as a point of attachment for muscles, aiding in locomotion. In vertebrates, it is replaced by the vertebral column.
25.Question: Differentiate between cartilaginous fish (Chondrichthyes) and bony fish (Osteichthyes) based on their skeleton.
Answer: Chondrichthyes (e.g., sharks) have a cartilaginous endoskeleton, while Osteichthyes (e.g., rohu) have a bony endoskeleton.
26.Question: Give two examples of amphibians and mention one adaptation they have for terrestrial life. Answer: Examples: Frogs, Salamanders. Adaptation: Lungs for respiration in adults (though still dependent on moist skin and water for breeding).
27. Question: What characteristic feature distinguishes reptiles from amphibians?
Answer: Reptiles have dry, scaly skin and lay amniotic eggs, allowing them to complete their life cycle entirely on land, unlike amphibians which require water for reproduction.
28. Question: Name two flight adaptations found in birds (Aves).
Answer: Birds have pneumatic bones (hollow bones filled with air) and their forelimbs are modified into wings with feathers.
29. Question: List three distinguishing features of mammals (Mammalia).
Answer: Mammals possess mammary glands for milk production, hair/fur on their body, and are homeothermic (warm-blooded).
30. Question: What is a 'key' in biological classification? How is it used?
Answer: A key is a taxonomic aid used for the identification of unknown organisms based on their similarities and dissimilarities. It consists of a series of contrasting characters, usually in pairs (couplet), where one choice leads to the identification of the organism or to another set of choices.
