NEET Unit Test - 1 - NEET MCQ

Euglenoids are unique in that they are photosynthetic in the presence of sunlight but can switch to a heterotrophic mode of nutrition in its absence, consuming other smaller organisms. Therefore, the correct answer is Option B, "heterotrophs."

Assertion A is true as slime molds indeed form fruiting bodies to disperse spores. Reason R is also true and is the correct explanation for A because the ability of spores to survive extreme conditions is crucial for the effective dispersal and lifecycle continuation of slime molds in varying environmental conditions.

Protozoans are diverse, mostly heterotrophic organisms found across various habitats including fresh water, sea water, and moist soil, making Option C correct. Options A, B, and D are incorrect as protozoans are primarily heterotrophs, have several subgroups like amoeboids and flagellates, and not all form symbiotic relationships.

Assertion A is false because algin is derived from brown algae, not red algae. Reason R is true as algin does indeed help in water retention and has various commercial uses. Therefore, Option C is the correct choice.

The correct sequence of events in the sexual cycle of fungi is as follows:

Plasmogamy: This is the initial step where the protoplasms of two fungal cells (usually from different mating types) fuse. However, the nuclei from these cells do not fuse immediately.
Karyogamy: This step involves the fusion of the nuclei from the fused cells. This process forms a diploid zygote nucleus.
Meiosis: Following karyogamy, the diploid zygote undergoes meiosis to form haploid spores that can develop into new fungal organisms.
Thus, the correct sequence is Plasmogamy, Karyogamy, and Meiosis, making Option C the correct choice.

Viroids are unique infectious agents made up solely of a short strand of RNA, without a protein coat, known for causing diseases in plants such as potato spindle tuber disease. This makes Option C correct. Option A incorrectly describes prions, not viroids; Option B is false as viroids are smaller than viruses and lack DNA; Option D describes lichens, not viroids.

In Basidiomycetes, the dikaryotic phase is crucial as it involves the coexistence of two haploid nuclei in one cell, which later fuse in a process called karyogamy. This phase is significant as it precedes the formation of basidiospores, which occur after nuclear fusion and meiosis within the basidium. This makes Option B the correct answer. Option A is incorrect as zoospores are not part of the Basidiomycetes lifecycle. Option C, while true for Basidiomycetes, does not specifically relate to the significance of the dikaryotic phase. Option D is incorrect because it misunderstands the necessity of nuclear fusion in spore formation in Basidiomycetes.

Statement i is incorrect because gymnosperms are characterized by having naked seeds that are not enclosed within fruits; this is a feature of angiosperms.
Statement ii is correct; some gymnosperms, like Cycas, have specialized coralloid roots associated with N2-fixing cyanobacteria.
Statement iii is correct; gymnosperms are heterosporous, producing both microspores and megaspores.
Statement iv is incorrect; while many gymnosperms like Pinus and Cedrus have branched stems, some, such as Cycas, have unbranched stems. Therefore, the correct answers are Statements ii and iii, making Option A correct.

• A-2: "Microsporangiate Strobili" are correctly described as male cones that produce microspores within microsporangia, essential for male gametophyte development, with Pinus being an example.
• B-3: "Coralloid Roots" are specialized roots associated with N2-fixing cyanobacteria, enhancing nitrogen intake, which is characteristic of Cycas.
• C-4: "Mycorrhiza" describes fungal associations that help in nutrient absorption from the soil, typically found in Pinus.
• D-1: The "Megaspore Mother Cell" undergoes meiotic division to produce megaspores that develop into a multicellular female gametophyte, as seen in Ginkgo.

Option A correctly matches each characteristic with its description and example, providing an accurate mapping of gymnosperm characteristics.

They are generally marine and mostly asymmetrical animals . These are primitive multicellular animals and have cellular level of organisation. Sponges have a water transport or canal system. Water enters through minute pores (ostia) in the body wall into a central cavity, spongocoel, from where it goes out through the osculum. This pathway of water transport is helpful in food gathering, respiratory exchange and removal of waste. Choanocytes or collar cells line the spongocoel and the canals. Digestion is intracellular. The body is supported by a skeleton made up of spicules or spongin fibres. Sexes are not separate (hermaphrodite), i.e., eggs and sperms are produced by the same individual. Sponges reproduce asexually by fragmentation and sexually by formation of gametes. Fertilisation is internal and development is indirect having a larval stage which is morphologically distinct from the adult.

Phylum echinodermata : 1. is correct and diagram is of ophiura
An excretory system is absent. Sexes are separate. Reproduction is sexual. Fertilisation is usually external. Development is indirect with free-swimming larva. Examples: Asterias (Star fish), Echinus (Sea urchin), Antedon (Sea lily), Cucumaria (Sea cucumber) and Ophiura (Brittle star).

Correct matching

Sperms are stored in seminal vesicles in cockroach.

Cockroaches undergo paurometabolous development, characterized by nymphs that resemble miniature adults. These nymphs progressively become adults through multiple molts, growing in size and maturity with each stage. This type of development is typical of insects that do not undergo a complete metamorphosis involving a pupal stage (Option A). Options C and D are not applicable to cockroaches as they neither hatch as winged adults nor start their life cycle in aquatic environments.

Cockroaches, like many other insects, possess an open circulatory system. This system is characterized by a limited network of blood vessels and a heart that pumps the hemolymph (blood) into the body cavity, where it directly bathes the organs. There is no distinction between blood and interstitial fluid in this type of system, unlike in closed circulatory systems.