Diversity In Living Organisms - Practice Test, Class 9 Science - Class 9 MCQ

Chloroplast in Spirogyra is spirally arranged and ribbon-shaped with pyrenoids.
Explanation:
Spirogyra is a filamentous green algae that belongs to the phylum Chlorophyta. It is known for its unique spiral-shaped chloroplasts. Here is a detailed explanation of the characteristics of chloroplasts in Spirogyra:
1. Spirally Arranged: The chloroplasts in Spirogyra are arranged in a spiral or helical pattern along the length of the cell. This arrangement allows maximum exposure of chlorophyll to light, enhancing photosynthesis.
2. Ribbon-shaped: The chloroplasts in Spirogyra are elongated and flattened, resembling ribbons or bands. This shape provides a larger surface area for chlorophyll molecules to capture sunlight.
3. Pyrenoids: Pyrenoids are small proteinaceous structures present within the chloroplasts of Spirogyra. They serve as centers for starch synthesis and storage. Starch is essential for energy storage in the cell.
4. Chlorophyll Content: Chloroplasts contain a high concentration of chlorophyll, the pigment responsible for capturing light energy during photosynthesis. The abundance of chlorophyll in Spirogyra enables efficient photosynthetic activity.
In conclusion, the chloroplasts in Spirogyra are spirally arranged and ribbon-shaped with pyrenoids. These features optimize the efficiency of photosynthesis in this filamentous green alga.

Needle shaped structure in Pinus plant is a leaf.
Explanation:
The needle-shaped structures found in Pinus plants are indeed leaves. These leaves are commonly referred to as needles due to their long and slender shape. Here's a detailed explanation:
1. Leaf Structure:
- Needles are the primary photosynthetic organs of Pinus plants.
- They are long, narrow, and have a pointed tip.
- Needles are covered with a waxy coating called cuticle, which helps reduce water loss and protect against environmental stresses.
2. Adaptations:
- The needle shape of leaves in Pinus plants is an adaptation to reduce water loss through transpiration.
- The reduced surface area of needles minimizes water loss, allowing the plant to survive in dry and arid conditions.
3. Functions:
- Needles perform photosynthesis, converting sunlight into chemical energy.
- They also aid in respiration and transpiration processes.
- Needles have a unique arrangement of vascular tissues that enable efficient water and nutrient transport.
4. Lifespan:
- Unlike deciduous trees, Pinus plants retain their needles for several years.
- The needles remain green and functional for multiple growing seasons, contributing to the plant's year-round photosynthetic activity.
5. Variations:
- Needles can vary in length, depending on the species of Pinus.
- Some species have needles measuring a few centimeters, while others can have needles reaching up to 30 cm.
In conclusion, the needle-shaped structure in Pinus plants is a leaf. These specialized leaves provide the plant with the ability to thrive in diverse environmental conditions.

Which among the following produce seeds?
The correct answer is D: Gymnosperms.
Explanation:
Gymnosperms are a group of plants that produce seeds. Here is a detailed explanation of the given options and why the correct answer is Gymnosperms:
A: Thallophyta
- Thallophyta is a division of plants that includes algae, fungi, and lichens.
- They do not produce seeds. Instead, they reproduce through spores.
B: Bryophyta
- Bryophyta, also known as mosses, are small, non-vascular plants.
- They do not produce seeds. They reproduce through spores.
C: Pteridophyta
- Pteridophyta refers to ferns and fern allies.
- They also do not produce seeds. They reproduce through spores.
D: Gymnosperms
- Gymnosperms are a group of seed-producing plants.
- They have naked seeds, meaning the seeds are not enclosed in a fruit.
- Examples of gymnosperms include conifers, cycads, and ginkgoes.
In conclusion, among the given options, only Gymnosperms (option D) produce seeds.

Amphibians of Plant Kingdom:
The correct answer is A: bryophytes.
Explanation:
Bryophytes are commonly known as the "Amphibians of Plant Kingdom" because they exhibit characteristics of both algae and terrestrial plants. They are a group of non-vascular plants that include mosses, liverworts, and hornworts. Here's a detailed explanation of why bryophytes are called "Amphibians of Plant Kingdom":
- Bryophytes are small, non-vascular plants that lack specialized tissues for conducting water and nutrients. This makes them similar to algae, which are also non-vascular.
- Like algae, bryophytes require a moist environment to survive and reproduce. They are typically found in damp areas such as forests, wetlands, and along streams.
- However, unlike algae, bryophytes have adapted to survive on land. They have specialized structures like rhizoids, which help them anchor to the substrate, and structures like gametangia, which protect their reproductive cells.
- Bryophytes also have a life cycle that alternates between a dominant gametophyte generation and a smaller sporophyte generation. This alternation of generations is a characteristic shared with other land plants.
- Due to these characteristics, bryophytes are considered as a transition between aquatic algae and land plants. They have some features of both groups, hence the nickname "Amphibians of Plant Kingdom".
In conclusion, bryophytes are called "Amphibians of Plant Kingdom" because they exhibit characteristics of both algae and terrestrial plants.

Answer:
Plant characteristics:
- Woody stem
- Leaves show reticulate venation
Possible options:
A: gymnosperm
B: monocot
C: dicot
D: pteridophyte
Explanation:
Gymnosperm:
- Gymnosperms have naked seeds, usually in cone-like structures.
- They do not have woody stems.
- Therefore, gymnosperms can be eliminated as the correct answer.
Monocot:
- Monocots have parallel venation in their leaves, not reticulate venation.
- Therefore, monocots can be eliminated as the correct answer.
Dicot:
- Dicots have reticulate venation in their leaves.
- They also have woody stems.
- Therefore, the plant in question fits the characteristics of a dicot.
Pteridophyte:
- Pteridophytes are vascular plants that reproduce via spores and do not have seeds.
- They do not have woody stems.
- Therefore, pteridophytes can be eliminated as the correct answer.
Conclusion:
Based on the given characteristics of a woody stem and reticulate venation in the leaves, the plant in question can be classified as a dicot (Option C).

Answer:
To prepare a temporary mount of Spirogyra, students should search for fresh specimens in a pond with stagnant water (Option D). Here's a detailed explanation:
Reasoning:
Spirogyra is a type of filamentous green algae that is commonly found in freshwater environments. It prefers calm, stagnant water bodies for growth and reproduction. Therefore, searching for fresh specimens in a pond with stagnant water would provide the best opportunity to find Spirogyra.
Explanation:
Here are the reasons why Option D is the correct answer:
1. Pond: Spirogyra is often found in ponds, where the water is relatively still and provides a suitable habitat for its growth.
2. Stagnant water: Spirogyra thrives in stagnant water, as it allows the algae to form long filaments or colonies. Stagnant water also reduces the chances of disturbance, ensuring the algae's growth.

Therefore, searching for fresh Spirogyra specimens in a pond with stagnant water would yield the best results for preparing a temporary mount.

Pneumatic bones is an important characteristic of:


Explanation:


1. Pneumatic bones:
- Pneumatic bones refer to bones that are hollow and filled with air sacs.
- These air sacs are connected to the respiratory system of the animal.
- Pneumatic bones contribute to the overall lightweight nature of the skeleton.
2. Aves (birds):
- Birds have pneumatic bones.
- Pneumatic bones in birds are connected to the respiratory system and allow for efficient respiration during flight.
- These hollow bones also contribute to the bird's ability to fly by reducing the overall weight of the skeleton.
- The presence of pneumatic bones is a unique characteristic of birds.
3. Reptiles, amphibians, and mammals:
- Reptiles and amphibians do not have pneumatic bones.
- They have solid bones without air sacs.
- Mammals also do not have pneumatic bones, with the exception of a few species like the platypus.
- Mammals have a different bone structure adapted for their specific needs.
4. Conclusion:
- Pneumatic bones are an important characteristic of aves (birds).
- Birds have evolved hollow bones filled with air sacs to aid in flight and reduce weight.
- Reptiles, amphibians, and mammals do not possess pneumatic bones as part of their skeletal structure.

Earthworm contains both male and female reproductive organs in the single organism, such organisms are called hermaphrodite. Though, earthworm is hermaphrodite but then also cross fertilisation is ensured in earthworms.

The True Fish: Dogfish

• Jellyfish: Jellyfish are not true fish. They belong to the phylum Cnidaria and are classified as invertebrates. They have a gelatinous body and lack a backbone.


• Starfish: Starfish, also known as sea stars, are not true fish either. They belong to the phylum Echinodermata and are classified as marine invertebrates. They have a unique radial symmetry and a spiny body.


• Dogfish: Dogfish is a true fish. It belongs to the family Squalidae and is a type of shark. Dogfish have cartilaginous skeletons, gill slits, paired fins, and a streamlined body that allows them to swim efficiently in water.


• Silverfish: Silverfish are not true fish. They belong to the phylum Arthropoda and are classified as insects. They have a silver-colored, elongated body and are known for their ability to consume carbohydrates, such as starch and cellulose.

Conclusion: Among the options given, the only true fish is the Dogfish.

Not an aerial adaptation of a bird:
- Presence of strong flight muscles: Birds have strong flight muscles that allow them to generate the necessary power for sustained flight. These muscles are highly developed and provide the necessary strength and agility for birds to navigate through the air.
- Presence of vertebral columns: Birds have vertebral columns, just like other animals. The vertebral column provides structural support and flexibility, allowing birds to maintain their shape and maneuver in flight.
- Streamlined body: A streamlined body is a key adaptation for birds that allows them to reduce air resistance and move through the air more efficiently. This adaptation helps birds achieve higher speeds and better maneuverability during flight.
- Forelimbs modified into wings: Birds have forelimbs that have evolved into wings, which are specialized appendages for flight. The wings provide lift and enable birds to soar, glide, and flap their way through the air.
Therefore, the correct answer is B: Presence of vertebral columns. Vertebral columns are not unique to birds and are found in many other animals as well. The other options listed are all specific adaptations that enable birds to fly effectively.

Group of Invertebrate Animals: Arthropoda
Arthropoda is a diverse group of invertebrate animals that includes insects, spiders, crustaceans, and other related organisms. Here is a detailed explanation of why arthropoda is the correct answer:
Mammalia (option A)
- Mammalia is a group of vertebrate animals, not invertebrates.
- Mammals have a backbone and are characterized by features such as mammary glands and hair or fur.
Pisces (option B)
- Pisces is a term used to refer to fish, which are also vertebrates.
- Fish have a backbone and are characterized by features such as gills and fins.
Reptilia (option C)
- Reptilia refers to reptiles, which are vertebrate animals.
- Reptiles have a backbone and are characterized by features such as scales, shelled eggs, and cold-bloodedness.
Arthropoda (option D)
- Arthropods are a diverse group of invertebrate animals that include insects, spiders, crustaceans, and more.
- They have jointed appendages, an exoskeleton, and a segmented body.
- Arthropods are the largest phylum in the animal kingdom and exhibit a wide range of adaptations for different habitats and lifestyles.
In summary, the correct answer is option D: Arthropoda. This group represents a diverse array of invertebrate animals with jointed appendages, an exoskeleton, and a segmented body.

Flightless Birds:
Penguin:
- Penguins are flightless birds that are well-adapted for life in the water.
- They have streamlined bodies, webbed feet, and wings modified into flippers.
- Penguins use their wings for swimming rather than flying.
Ostrich:
- The ostrich is the largest and heaviest living bird.
- It is native to Africa and is known for its long, powerful legs.
- Ostriches are flightless but are incredibly fast runners, reaching speeds up to 70 km/h (43 mph).
Kiwi:
- The kiwi is a small flightless bird native to New Zealand.
- It is about the size of a chicken and has a long beak and short wings.
- Kiwis are nocturnal and have a highly developed sense of smell.
All of these:
- All the options listed (penguin, ostrich, and kiwi) are flightless birds.
- They have different adaptations and characteristics, but they share the common trait of being unable to fly.
In conclusion, the correct answer is D: all of these as all the options mentioned (penguin, ostrich, and kiwi) are flightless birds.

The Science of Classification: Taxonomy
Taxonomy is the science of classification that deals with the identification, naming, and categorization of organisms. It is a vital field in biology that allows scientists to organize and understand the diversity of life on Earth. Here is a detailed explanation of why taxonomy is the correct answer:
1. Definition of Taxonomy:
- Taxonomy is the branch of science that involves classifying and categorizing living organisms based on their characteristics and relationships.
- It aims to organize the vast array of species into a hierarchical system that reflects their evolutionary history and shared traits.
2. Purpose of Taxonomy:
- Taxonomy provides a standardized system for naming and classifying organisms, ensuring clear communication between scientists across different regions and languages.
- It helps scientists identify and study relationships between different species, allowing for the discovery of evolutionary patterns and the development of evolutionary theories.
- Taxonomy is crucial for conservation efforts, as it helps identify endangered species and develop strategies for their preservation.
3. Taxonomic Hierarchy:
- Taxonomy organizes species into a hierarchical system known as the taxonomic hierarchy.
- The hierarchy consists of several levels, including domain, kingdom, phylum, class, order, family, genus, and species.
- Each level represents a different level of classification, with species being the most specific category.
4. Taxonomic Methods:
- Taxonomists use various methods to classify organisms, including morphological, anatomical, genetic, and molecular characteristics.
- Traditional taxonomy relies on observable traits, such as physical appearance, behavior, and reproductive features.
- Modern taxonomy incorporates molecular techniques, such as DNA sequencing, to determine genetic relationships between species.
5. Importance of Taxonomy:
- Taxonomy provides a foundation for other biological sciences, including ecology, evolution, and genetics.
- It enables scientists to accurately identify and distinguish between different species, which is fundamental for studying biodiversity and ecosystem dynamics.
- Taxonomy also has practical applications in agriculture, medicine, and forensics, helping to identify pests, develop new drugs, and solve crimes.
In conclusion, the science of classification is called taxonomy. It is a critical field that allows scientists to organize and understand the diversity of living organisms. By categorizing species based on their characteristics and relationships, taxonomy provides a standardized system for naming, identifying, and studying organisms.

Homo: generic name :: sapiens: ________.
The correct answer is A. species name.
Explanation:
- The term "Homo" is a generic name used to refer to the genus that includes modern humans and extinct human species.
- Similarly, "sapiens" is a specific name used to refer to the species Homo sapiens, which represents modern humans.
- In biological classification, the generic name is used to group similar species together, while the specific name differentiates between different species within the same genus.
- Therefore, "species name" is the appropriate term to complete the analogy, as it refers to the specific name given to a particular species.
- The genus name (Homo) is a higher-level classification, whereas the species name (sapiens) is a lower-level classification that further specifies the particular species within the genus.
- Hence, the analogy can be understood as: Homo is to generic name as sapiens is to species name.

Answer:
Definition of a species:
- A species is a group of organisms that are capable of interbreeding and producing fertile offspring.
- Members of the same species share common characteristics and are genetically similar.
Explanation:
- In biology, the classification of living organisms is hierarchical, with species being one of the basic units of classification.
- A species is a distinct group of organisms that have the potential to interbreed and produce viable offspring.
- Freely interbreeding organisms within a group ensure the genetic continuity of that species.
- Reproductive isolation between different species prevents interbreeding and maintains the genetic distinctiveness of each species.
Other options:
- Genera: Genera is a higher taxonomic rank that groups similar species together. It is a level above species in the hierarchy.
- Family: Family is a higher taxonomic rank that groups similar genera together. It is a level above genera in the hierarchy.
- Class: Class is a higher taxonomic rank that groups similar families together. It is a level above family in the hierarchy.
Conclusion:
- A group of freely interbreeding organisms constitutes a species.
- Species is the basic unit of classification in biology, representing a distinct group of organisms capable of interbreeding.