Diversity in Living Organisms

Species are groups of actually or potentially interbreeding populations which are reproductively isolated from other such groups. Interbreeding also called as hybrid is the result of combining the qualities of two organisms of different breeds, varieties, species or genera through sexual reproduction. 

Animal prey defence includes camouflage, causing alarm of fright and mimicry. But it does not include soft skin. So, the correct option is 'soft skin'

Animals can be distinguished based in number of germ layers present. There are generally three germ layers viz. endoderm, mesoderm and ectoderm. Based on this animals are said as monoblasts, diploblasts and triploblasts. 

Instinct and mimicry are the behaviours which are shown by the animals. Instinct is the ability to judge an event and give response accordingly. Mimicry is performed in order to protect them. Bluffing is an unusual behaviour which may be seen due to fear. This may be used as a form of communication for protection against the predator.

A bird's beak can tell us what type of food it eats. Short stout cone shaped beak is an adaptation to help crack nuts and seeds. For example the sparrows and finches have this type of beaks to crack the nuts. The hawk also has short beak but their upper beak is a hook type to tear flesh.  

The kingdom Protista includes diverse forms of predominantly water-dwelling, eukaryotic unicellular micro-organisms. Some of these organisms are animal-like(protozoan), others resemble plants (algal protists), and others demonstrate the characters of fungi. In kingdom Protista, all organism are unicellular during most phases of their life cycle or are colonial. Thus option D is the correct answer. 

In the five-kingdom classification system, all unicellular eukaryotic organisms (those with a true nucleus) are placed in the kingdom Protista.

Kingdom protists, Fungi, Plantae, and Animalia belong to domain eukarya and include only eukaryotic organisms. Kingdom monera includes unicellular prokaryotic organisms that lack a well-defined nucleus and other membrane-bound organelles.Thus, the correct answer is option A.

Monera, Protista, Fungi, Plantae, and Animalia are the five kingdoms proposed by R.H. Whittaker. Therefore, all the options listed are valid kingdoms.

(A) The cell wall is a structural layer around types of the cell outside the cell membrane which provides the cell with structural support and protection found in algae, fungi, plants, bacteria and archaea.

The first organisms that appeared on earth resembled single-celled life forms called archaea that can live in extreme environments such as hot springs and deep-sea vents. They were prokaryotic heterotrophs and used inorganic chemicals from the environment for carbon fixation and this process is called chemoautotrophy. They were anaerobic in nature because free oxygen was absent during primitive environment on earth.

The earliest living organisms were prokaryotes which later on evolved to give rise to eukaryotes and photosynthesizing organisms.

• In biology, an atavism is a modification of a biological structure whereby an ancestral trait reappears after having been lost through the evolutionary change in previous generations. For example, the Appearance of ancestral characters in the new borne, such as the tail, multiple mammae, etc in humans, Extra toes of the modern horse, Reappearance of prothoracic wings in insects, etc.
• Hence Appearance of ancestral characters in the new borne, such as the tail, multiple mammae, etc., are known as an atavism.
• So, the correct answer is 'Atavism'.

Plant cells sometimes form mineral crystals. Calcium carbonate occurs as a mass of crystals around a cellulose core to form cystolith (eg, leaf of Banyan). In several plants, calcium oxalate forms needle-like raphides, prismatic crystals, star-shaped sphaeraphides or Druses or powdery mass named as crystal sand.