1
A group of students observed a pond and noted down the following characteristics of some organisms found in it:
- Organism A: Unicellular, eukaryotic, moves using flagella, performs photosynthesis in the presence of light but becomes heterotrophic in its absence.
- Organism B: Unicellular, prokaryotic, no true nucleus, survives in extreme conditions like hot springs.
- Organism C: Multicellular, eukaryotic, cell wall made of chitin, obtains nutrients by absorption from decaying matter.
- Organism D: Multicellular, eukaryotic, autotrophic, cell wall made of cellulose, has flowers.
Based on these observations, identify the kingdoms to which Organism A and Organism C belong. Justify your answer with one key characteristic for each. [3 marks]
2
Assertion (A): All unicellular organisms are grouped under the Kingdom Protista.Reason (R): Protista are characterized by the presence of a true nucleus and membrane-bound organelles.(a) Both A and R are true and R is the correct explanation of A.(b) Both A and R are true but R is not the correct explanation of A.(c) A is true but R is false.(d) A is false but R is true. 1mark
3
Case Study: A researcher is studying a collection of organisms from a dense forest. She finds an organism that is multicellular, lacks chlorophyll, has a cell wall made of chitin, and reproduces using spores. It was found growing on decaying wood.(i) Which kingdom is this organism most likely to belong to? [1 mark](ii) State two key characteristics from the case study that helped you identify the kingdom. [2 marks](iii) How does this organism contribute to the ecosystem? 1mark
4
A student is trying to classify a fern. They observe that it has true roots, stems, and leaves, and possesses vascular tissues (xylem and phloem). However, they also notice that it requires water for reproduction and does not produce seeds.(a) To which major plant group does this organism belong? [1 mark](b) Explain why this organism is considered a Pteridophyte and not a Bryophyte, despite both lacking seeds. 2marks
5
Assertion (A): India is considered a biodiversity hotspot.Reason (R): India is home to a large number of endemic species and has diverse habitats.(a) Both A and R are true and R is the correct explanation of A.(b) Both A and R are true but R is not the correct explanation of A.(c) A is true but R is false.(d) A is false but R is true. 1mark
6
A scientist observes an organism that exhibits bilateral symmetry, a triploblastic body organization, and a flattened body. It has a single opening for both ingestion and excretion.(a) To which phylum would this organism most likely belong? [1 mark](b) Name one feature that distinguishes it from an annelid. [1 mark](c) How does its single opening for ingestion and excretion pose a limitation compared to organisms with two openings? 2marks
7
Consider the following two organisms:
- Organism X: A simple aquatic organism with pores all over its body, through which water circulates for feeding and respiration. It is sessile.
- Organism Y: An aquatic organism with a soft body, often protected by a shell, and showing organ system level organization. It moves using a muscular foot.
Identify the phyla to which Organism X and Organism Y belong. Provide one reason for each identification. [4 marks]
8
You are given two slides: Slide 1 shows organisms that are unicellular, prokaryotic, and can survive in extreme environments. Slide 2 shows organisms that are unicellular, eukaryotic, and have a cell wall made of cellulose or no cell wall.(a) Identify the kingdom to which the organisms in Slide 1 belong. [1 mark](b) Identify the kingdom to which the organisms in Slide 2 belong. [1 mark](c) What is the main difference in cellular organization between the organisms in Slide 1 and Slide 2? 1mark
9
Assertion (A): Binomial nomenclature provides a unique scientific name for every organism.Reason (R): The scientific name consists of a genus name and a species name, both of which are universal and standardized.(a) Both A and R are true and R is the correct explanation of A.(b) Both A and R are true but R is not the correct explanation of A.(c) A is true but R is false.(d) A is false but R is true. 1mark
10
A teacher shows a picture of a frog and asks the students to classify it. One student says it is a reptile, while another says it is an amphibian.(a) Which student is correct and why? [2 marks](b) Name one characteristic that distinguishes amphibians from reptiles. 1mark
11
Case Study: A group of students is exploring a riverbed. They find small, segmented worms with a distinct body cavity and bristles. Further upstream, they find organisms with a hard exoskeleton, jointed appendages, and a segmented body.(a) Identify the phylum of the segmented worms found in the riverbed. [1 mark](b) Name the phylum of the organisms with exoskeletons and jointed appendages. [1 mark](c) Explain one advantage of having a body cavity for the segmented worms. [1 mark](d) What function does the exoskeleton serve for the organisms found upstream? 1mark
12
Why are fungi considered to be a separate kingdom in the five-kingdom classification system, distinct from plants? Give two reasons. 2marks
13
Assertion (A): Viruses are not placed in any of the five kingdoms.Reason (R): Viruses exhibit cellular organisation and carry out metabolic activities independently.(a) Both A and R are true and R is the correct explanation of A.(b) Both A and R are true but R is not the correct explanation of A.(c) A is true but R is false.(d) A is false but R is true. 1mark
14
A researcher discovers a new species of flowering plant. The seeds of this plant are not enclosed within a fruit and are often exposed on cones.(a) Which group of plants does this description most closely match? [1 mark](b) Explain the contradiction in the description provided by the researcher. 2marks
15
A student observes a microscopic organism under a microscope. It is unicellular, eukaryotic, and has a contractile vacuole. It can perform photosynthesis in the presence of light but obtains nutrients from other sources in the absence of light.(a) To which kingdom would this organism most likely belong? [1 mark](b) Provide a reason for your classification, focusing on the mode of nutrition. 1mark
16
Case Study: The Western Ghats of India are known for their high rainfall, dense forests, and a significant number of endemic species. This region is crucial for biodiversity conservation.(i) What is meant by an 'endemic species'? [1 mark](ii) Explain why a region with high rainfall and dense forests supports a large number of species. [2 marks](iii) Why is biodiversity conservation important in regions like the Western Ghats? 1mark
17
Assertion (A): The hierarchical classification system (Kingdom, Phylum, Class, Order, Family, Genus, Species) reflects evolutionary relationships.Reason (R): At each lower level of classification, organisms share more common features and are more closely related.(a) Both A and R are true and R is the correct explanation of A.(b) Both A and R are true but R is not the correct explanation of A.(c) A is true but R is false.(d) A is false but R is true. 1mark
18
Observe the given diagram of a plant:[Imagine a diagram of a fern plant with labeled roots, stem, and leaves, and perhaps a cross-section of the stem showing vascular bundles.](a) To which class of plants does this organism belong? [1 mark](b) What is the significance of the structures labeled 'vascular tissues' (xylem and phloem) for this plant? [2 marks](c) Explain why this plant still depends on moist conditions for reproduction, despite having well-developed vascular tissues. 1mark
19
A group of scientists is classifying an animal. They note that it has a backbone, mammary glands, and hair.(a) Which sub-phylum and class would this animal belong to? [2 marks](b) Name one other characteristic that supports this classification. 1mark
20
Case Study: A new species of bacteria is discovered in the deep-sea hydrothermal vents, an extreme environment. Scientists observe that it is unicellular and lacks a membrane-bound nucleus.(a) To which kingdom would this bacterium be assigned? [1 mark](b) Mention one characteristic that is crucial for placing it in this kingdom. [1 mark](c) Explain why this characteristic is important for classification. 1mark
Answers
1
Organism A: Kingdom Protista. Reason: It is unicellular, eukaryotic, and shows both autotrophic and heterotrophic modes of nutrition depending on the environment. Organism C: Kingdom Fungi. Reason: It is multicellular, eukaryotic, has a cell wall made of chitin, and obtains nutrients by absorption from decaying matter.
2
(d) A is false but R is true. (Unicellular organisms are found in Monera, Protista, and even Fungi like yeast.)
3
(i) Kingdom Fungi.(ii) Multicellular, eukaryotic, cell wall made of chitin, obtains nutrients by absorption from decaying matter.(iii) It acts as a decomposer, breaking down dead organic matter and recycling nutrients in the ecosystem.
4
(a) Pteridophytes.(b) Ferns are classified as Pteridophytes because they possess true roots, stems, and leaves, and have vascular tissues for transport, which are advancements over Bryophytes. However, like Bryophytes, they still require water for reproduction (fertilization) and do not produce seeds.
5
(a) Both A and R are true and R is the correct explanation of A.
6
(a) Phylum Platyhelminthes (flatworms).(b) Presence of a backbone (vertebrate) or segmented body with a body cavity (annelid).(c) A single opening limits the efficiency of digestion and waste removal, as processes of ingestion and egestion occur simultaneously through the same opening, potentially leading to contamination.
7
Organism X: Phylum Porifera. Reason: It is multicellular with pores all over its body, lacking true tissues and organs, and is sessile. Organism Y: Phylum Mollusca. Reason: It has a soft body, often with a shell, organ system level organization, and moves using a muscular foot.
8
(a) Kingdom Monera.(b) Kingdom Protista.(c) Organisms in Slide 1 are prokaryotic (lack a true nucleus), while organisms in Slide 2 are eukaryotic (possess a true nucleus).
9
(a) Both A and R are true and R is the correct explanation of A.
10
(a) The student who said it is an amphibian is correct. Frogs belong to the class Amphibia, characterized by a life cycle that typically involves an aquatic larval stage (like tadpoles) and a terrestrial or semi-aquatic adult stage. They also have moist, permeable skin.(b) Amphibians typically undergo metamorphosis, while reptiles do not. Amphibians have moist skin, while reptiles have dry, scaly skin.
11
(a) Phylum Annelida.(b) Phylum Arthropoda.(c) A body cavity (coelom) provides space for the development and functioning of organs, allows for better circulation of nutrients and waste, and facilitates movement through hydrostatic pressure.(d) The exoskeleton provides protection, support, prevents water loss, and serves as a point of attachment for muscles, enabling efficient movement.
12
1. Fungi are heterotrophic and obtain nutrients by absorption, whereas plants are autotrophic and produce their own food through photosynthesis.
2
Fungal cell walls are made of chitin, while plant cell walls are primarily made of cellulose.
13
(d) A is false but R is true. (Viruses are acellular, lack cellular organization, and are inactive outside a host cell. They do not carry out metabolic activities independently.)
14
(a) Gymnosperms.(b) The description is contradictory because Gymnosperms are characterized by naked seeds, while the description mentions seeds enclosed within fruits, which is a characteristic of Angiosperms.
15
(a) Kingdom Protista.(b) The organism is unicellular and eukaryotic, fitting the general description of Protista. Its ability to perform photosynthesis in light and be heterotrophic in the absence of light indicates a mode of nutrition that can be characteristic of some protists (like Euglena).
16
(i) An endemic species is a species that is found only in a particular geographic region and nowhere else in the world.(ii) Regions with high rainfall and dense forests provide abundant water, nutrients, and diverse habitats, which support a wide variety of plant and animal life, leading to high species richness.(iii) Biodiversity conservation is important in the Western Ghats to protect the unique endemic species found there, maintain ecological balance, ensure the availability of resources, and prevent the loss of invaluable genetic diversity.
17
(a) Both A and R are true and R is the correct explanation of A.
18
(a) Class Pteridophyta.(b) Vascular tissues (xylem and phloem) are responsible for the transport of water and minerals from the roots to the rest of the plant (xylem) and the transport of manufactured food from the leaves to other parts of the plant (phloem). This allows for efficient nutrient distribution in a more complex plant body.(c) Despite having vascular tissues, Pteridophytes still depend on moist conditions for reproduction because their male gametes are flagellated and need to swim through water to reach the female gametes for fertilization.
19
(a) Sub-phylum: Vertebrata; Class: Mammalia.(b) Presence of hair, and/or giving birth to live young, and/or production of milk by mammary glands.
20
(a) Kingdom Monera.(b) Lack of a membrane-bound nucleus (prokaryotic nature).(c) The presence or absence of a well-defined nucleus is a fundamental characteristic used to distinguish between prokaryotes (like bacteria) and eukaryotes (found in Protista, Fungi, Plantae, and Animalia). This distinction is considered a major evolutionary divergence.
