Diversity in Living Organisms Class 9 Questions and Answers – The NCERT Solutions for Class 9 Science help students prepare effectively for their examinations by providing them with a comprehensive set of solutions. These solutions serve as a vital resource for students who may find it difficult to locate the answers to the questions on their own. Students can use these solutions to build a solid foundation in Science and achieve academic success.
Diversity in Living Organisms Class 9 Questions and Answers
Q. Why do we classify organisms?
Answer – We classify organisms to make it easier to study and understand the vast diversity of living organisms on Earth. Classification helps us to identify, name, and organize species based on their shared characteristics and evolutionary relationships.
Q. Give three examples of the wide range of diversity you observe in the nearby life types.
Answer – Some examples of variations observed in life forms are:
(a) Range in size from a small frog to a big whale.
(b) Range in size and growth pattern from a small creeper to a large eucalyptus tree.
(c) Range in colour and appearance from a dull black cuckoo to a vibrant and colourful peacock.
Q. Which of the following do you believe to be a more fundamental trait for categorising organisms?
(A) The area in which they reside.
(b) The types of cells that make them up. Why?
Answer – It is more basic to classify organisms according to the type of cells they are made of than according to their habitat. This is due to the fact that while creatures with comparable cell structures may exist in many habitats, those with differing cell structures will exhibit various traits. Cell structure is a more dependable and essential trait for classification as a result.
Q. What is the primary difference among organisms based on which it is made?
Answer – Living organisms are primarily categorized based on their cellular organization, which is either prokaryotic or eukaryotic. Prokaryotic cells are simple in structure and do not have a nucleus or membrane-bound organelles, while eukaryotic cells are more complex and contain a nucleus and various organelles. Further classification of organisms into subclasses is based on additional features, such as their nutrition, cell walls, and structural characteristics.
Q. What characteristics are used to categorize plants and animals?
Answer – The categorization of plants and animals is based on the following:
- Presence or absence of a cell wall: This is the most fundamental consideration in classification. It differentiates plants (with a cell wall) from animals (without a cell wall).
- Mode of nutrition: The mechanism through which organisms acquire their nutrients is used as a criterion for classification. Autotrophs (such as plants) and heterotrophs (such as animals) are categorized differently based on their mode of nutrition.
- Other features: Other characteristics such as reproductive system, body symmetry, and the presence or absence of specialized tissues and organs are also used to further categorize organisms. These characteristics may be used in combination with the presence or absence of a cell wall and mode of nutrition to create a comprehensive system of classification.
Q. Which species fall under the category of “primitive,” and how do they differ from those classified as “advanced”?
Answer – Primitive organisms are characterized by a simple and basic cell arrangement, mechanism, and structure, with no division of labor observed. In contrast, advanced organisms have millions of cells grouped into various organs performing different functions, such as mammals.
Q. Will complex organisms and advanced organisms be the same? Why?
Answer – Advanced organisms, also known as complex organisms, have a higher level of organization than primitive organisms, resulting in multiple specialized cell arrangements that support the organism’s various functions and processes. This increased complexity allows for more sophisticated bodily processes, such as complex nervous systems, advanced sensory organs, and intricate biochemical pathways.
Q. What standard is used to determine whether an organism belongs to the Monera or Protista kingdom?
Answer – One of the most significant differences in organism classification is the presence or absence of a nuclear membrane. Organisms without nuclear membranes are classified as Monera, while those with well-defined nuclear membranes are classified as Protista.
Q. Which kingdom will you assign a single-celled, eukaryotic, photosynthetic organism to?
Answer – An organism that is single-celled, eukaryotic, and photosynthetic would typically be classified in the Kingdom Protista. Many protists, such as algae, possess these characteristics and are classified as single-celled eukaryotes that can produce their own food through photosynthesis.
Q. Which category in the categorization hierarchy will have the smallest organisms and the greatest number of species with the greatest degree of similarity?
Answer –
(a) The Kingdom Monera has the smallest number of organisms and the maximum characteristics in common, including:
- They are unicellular organisms with simple cell structures.
- They lack a well-defined nucleus and other membrane-bound organelles.
- They reproduce asexually through binary fission or other similar processes.
- They exhibit a wide range of metabolic pathways, including aerobic and anaerobic respiration and photosynthesis.
(b) The Kingdom Animalia has the largest number of organisms, characterized by:
- They are multicellular organisms with complex cell structures.
- They possess a well-defined nucleus and various membrane-bound organelles.
- They are heterotrophic and obtain their nutrients through ingestion and digestion of other organisms.
- They exhibit a wide range of body plans, from simple radial symmetry to complex bilateral symmetry.
Q. Which plant division has the most basic organisms?
Answer – Algae or Thallophyta have the simplest organism among plants, characterized by:
- They are mostly aquatic and are found in a variety of habitats.
- They are unicellular or multicellular organisms with a simple body structure.
- They do not have roots, stems, or leaves like higher plants.
- They reproduce asexually or sexually through different mechanisms.
- They are photosynthetic and play a significant role in the production of oxygen and the food chain in aquatic ecosystems.
Q. How do pteridophytes and phanerogams differ from one another?
Answer –
| Feature | Pteridophytes | Phanerogams |
|---|---|---|
| Seed Production | No | Yes |
| Flower Production | No | Yes |
| Vascular Tissue | Present | Present |
| Reproduction | By spores | By seeds |
| Main Examples | Ferns, horsetails | Trees, shrubs, herbs |
| Dominant Generation | Sporophyte | Sporophyte |
| Habitat | Mostly terrestrial | Terrestrial and aquatic |
| Size | Generally smaller | Can vary in size |
Q. What are the differences between angiosperms and gymnosperms?
Answer – Gymnosperms and angiosperms differ in terms of their seed structure. Gymnosperms produce seeds that are not covered by any protective structure, making them naked seeds. On the other hand, angiosperms produce seeds that are enclosed within a protective structure, such as a fruit or seed coat. This fundamental difference in seed structure is a defining characteristic that distinguishes the two groups of plants.
Q. How are coelenterate animals different from poriferan animals?
Answer –
| Poriferan Animals | Coelenterate Animals |
|---|---|
| Have a porous body with numerous openings called ostia | Have a sac-like body with a single opening called a mouth |
| Do not have true tissues or organs | Have true tissues and organs |
| Lack a definite shape and symmetry | Have a definite shape and radial symmetry |
| Have a primitive nervous system and no sensory organs | Have a simple nervous system and sensory organs such as tentacles |
| Have no digestive system, with food particles taken in through ostia and expelled through a larger opening called the osculum | Have a digestive system with a central cavity and a single opening for both ingestion and elimination |
| Reproduce both sexually and asexually | Reproduce both sexually and asexually |
| Examples include sponges | Examples include jellyfish and coral |
Q. How are arthropods and annelid animals different?
Answer –
| Characteristic | Annelid Animals | Arthropods |
|---|---|---|
| Body Segmentation | True segmentation with repeating units | Segmentation with fused body regions |
| Body Cavity | Coelom present | Hemocoel present |
| Exoskeleton | Absent | Present |
| Appendages | Few or absent | Multiple pairs of jointed legs and/or wings |
| Circulatory System | Closed circulatory system | Open circulatory system |
| Respiratory System | Gills or skin diffusion | Gills, tracheae, or book lungs |
| Nervous System | Ventral nerve cord | Ventral nerve cord and complex brain |
| Reproduction | Sexual or asexual | Sexual with various modes of fertilization |
Q. How do amphibians and reptiles differ from one another?
Answer –
| Amphibians | Reptiles | |
|---|---|---|
| Body temperature | Cold-blooded (ectothermic) | Cold-blooded (ectothermic) |
| Skin | Thin, smooth, moist skin without scales | Dry skin covered with scales |
| Respiration | Breathe through skin and lungs | Breathe only through lungs |
| Reproduction | Lay eggs in water or moist environments | Lay eggs on land with tough shells |
| Limbs | Typically have four limbs, with webbed feet for swimming | Limbs adapted for crawling or walking on land |
| Habitat | Require moist habitats, such as near water | Can live in a variety of habitats, including deserts, forests, and grasslands |
Q. What distinctions can be made between creatures in the Aves group and those in the mammalian group?
Answer –
| Characteristic | Aves (Birds) | Mammals |
|---|---|---|
| Body covering | Feathers | Hair/fur |
| Body temperature regulation | Endothermic (warm-blooded) | Endothermic (warm-blooded) or ectothermic (cold-blooded) |
| Skeleton | Lightweight bones with air sacs | Heavy bones |
| Reproduction | Lay eggs with hard shells | Give birth to live young |
| Breathing | Air sacs in addition to lungs | Lungs only |
| Heart | Four-chambered heart | Four-chambered heart |
| Digestive system | Lack teeth and have a crop and gizzard | Have teeth and a well-developed stomach |
| Sight | Good color vision and sharp eyesight | Limited color vision and sharpness varies among species |
Q. What benefits do classifications of organisms have?
Answer – The advantages of classifying organisms are –
- Classification helps in studying common features of organisms.
- Simplifies the study of scientific experiments.
- Helps in understanding the interrelation of organisms and their interactions with humans.
- Allows for commercial applications through crossbreeding and genetic modification.
Q. What considerations would you use to decide which of two qualities to include in a classification hierarchy?
Answer – The hierarchical classification of organisms is based on the following principles:
- Gross or fundamental characteristics are used as the basis for the start of the hierarchy.
- Fine or specific characteristics are used as the basis for further classification steps.
- For example, human beings are categorised under vertebrates as they possess the vertebral column, which is a fundamental characteristic of this group.
- For tetrapods, the existence of four limbs is considered as a fundamental characteristic.
- In the case of mammals, the presence of mammary glands is used as a fundamental characteristic for their classification.
Q. Why did organisms get categorised into five kingdoms?
Answer – The basic for grouping organisms into five kingdoms are –
- Number of cells: The first criterion for classification is based on the number of cells present in the organism.
- Cell arrangement and layers: The next criterion is based on the arrangement and number of cell layers present in the organism.
- Cell wall: Another important factor for classification is the presence or absence of a cell wall.
- Mode of nutrition: Classification of complex organisms is based on the mode of intake of nutrition, such as autotrophs or heterotrophs.
- Organisational level: Classification is also based on the organization level, such as cellular or multicellular.
Q. What are the Plantae’s primary divisions? What underlies these divisions?
Answer –
| Division | Basis of Division |
|---|---|
| Thallophyta | Simple, non-vascular plants without differentiated stems, leaves, or roots |
| Bryophyta | Simple, non-vascular plants with differentiated stems and leaves, but lacking true roots |
| Pteridophyta | Vascular plants with true stems, leaves, and roots, but lacking seeds |
| Gymnosperms | Vascular plants with true stems, leaves, and roots, and with seeds that are not enclosed in a fruit |
| Angiosperms | Vascular plants with true stems, leaves, and roots, and with seeds that are enclosed in a fruit |
Q. How are the methods for classifying plant divisions different from those for classifying animal subgroups?
Answer –
Criteria for deciding divisions in plants:
- Basic cell structure (prokaryotic or eukaryotic) for dividing into Thallophytes and Bryophytes.
- Visibility of seeds for dividing into Gymnosperms and Angiosperms.
- Presence or absence of vascular tissue for dividing into Vascular and Non-vascular plants.
Criteria for deciding subgroups among animals:
- Presence or absence of a backbone (vertebrates and invertebrates).
- Type of symmetry (radial or bilateral).
- Presence or absence of a coelom (acoelomates, pseudocoelomates, and coelomates).
- Type of embryonic development (protostomes and deuterostomes).
Q. Describe the further division of Vertebrata’s animal species into subgroups.
Answer –
Vertebrata has Two subclasses –
a. Pisces
b. Tetrapod.
Pisces includes animals with streamlined bodies, tails, and fins for swimming. Tetrapod includes animals with four limbs for movement on land or in water.
Tetrapod is further classified into four groups: Amphibia, Reptilia, Aves, and Mammalia.
- Amphibia – Amphibia are adaptable animals that can live on land and in water, with specialized organs for breathing underwater.
- Reptilia – Reptilia are crawling animals with thick skin that can withstand extreme temperatures.
- Aves – Aves are birds with modified forelimbs for flight, beaks instead of teeth, and feathers covering their bodies.
- Mammalia – Mammalia are animals with hair covering their skin, mammary glands for nurturing their young, and most are viviparous (give birth to live young).