Diversity in Living Organisms

This is the correct option. An earthworm is not an autotrophic organism. It is rather a heterotrophic organism.

This is the correct option. Algae are autotrophic organisms that are capable of synthesing their own food.

This is the correct option. Alga provides food to the fungus, which it prepares by the process of photosynthesis. 

Urochordates (tunicates) possess a simple, tubular, ventral heart that can reverse direction. This primitive heart structure contrasts with the more complex chambered hearts found in vertebrates (Vertebrata) and other chordate groups.

When two different species resemble each other in external appearance, it's called mimicry. Kraits (venomous snakes) and Lycodon (non-venomous snakes) look very similar, which is an example of Batesian mimicry where a harmless species mimics a harmful one for protection.

The allantois is an extraembryonic membrane in mammalian embryos that functions in nutrient transport from the yolk sac, waste storage (excretion), and early gas exchange (respiration). Protection is primarily provided by the amnion and chorion, not the allantois.

The blood fluke (Schistosoma) is dioecious with separate male and female organisms, unlike most other flukes. Liver fluke, hydra, and earthworm are all hermaphrodites possessing both male and female reproductive organs.

Prokaryotes are characterized by the absence of a membrane-bound nucleus, which is the defining feature that distinguishes them from eukaryotic cells. They possess DNA (though not enclosed in a nuclear membrane), some have cell walls, and certain prokaryotes like cyanobacteria contain chlorophyll for photosynthesis. The nucleus is a eukaryotic organelle that prokaryotes completely lack.

Phycoerythrin is a red pigment-protein complex found in red algae (Rhodophyta), including Gracilaria species. This accessory pigment absorbs blue-green light and allows red algae to perform photosynthesis at greater depths where other light wavelengths are filtered out. Gracilaria is an economically important red alga used in agar production. The other options - Sargassum (brown algae), Caulerpa (green algae), and Ulva (green algae) - do not contain phycoerythrin.

PAS (Periodic acid-Schiff) stains carbohydrates and carbohydrate-rich structures like glycogen, glycoproteins, and mucopolysaccharides. It stains fungal cell walls (due to polysaccharides), basement membranes, and glycogen deposits. Lipids are not carbohydrates and are not stained by PAS - fat stains include Oil Red O and Sudan dyes.

Most snakes have only one functional lung - the right lung is well-developed while the left lung is either very small or completely absent. This adaptation allows for their elongated body shape. The single lung is quite elongated and can extend far into the body cavity.

Among the given organisms, Mycoplasma pneumoniae has the smallest genome size.

Gracilicutes (Latin: gracilis, slender, and cutis, skin, referring to the cell wall) is a controversial taxon in bacterial taxonomy. Firmicutes refers to the gram positive class of bacteria.

New World monkeys (Platyrrhini) possess prehensile tails used for grasping branches, while Old World monkeys (Catarrhini) lack this adaptation. This anatomical feature is a key distinction between the two primate groups in the Americas versus Africa/Asia.

Housefly, dragonfly, and butterfly are all insects belonging to the phylum Arthropoda and class Insecta. The other options mix different phyla or classes - 'worms' include annelids and platyhelminthes, 'fish' mix fish, molluscs, and echinoderms, and the sea creatures represent three different phyla.