Identify the correct statement about the circulatory system: MCQ with Answer and Explanation

Explanation:
Bacteria exhibit diverse nutritional modes; some are autotrophic (photosynthetic like cyanobacteria or chemosynthetic), while others are heterotrophic (saprophytic or parasitic). Fungi are eukaryotic organisms, characterized by having a true nucleus and membrane-bound organelles, and are heterotrophic. Viruses are considered non-living outside a host cell because they lack metabolic machinery and cannot replicate independently; they only exhibit living characteristics inside a host. Thus, statements 1 and 3 are correct.

Explanation:
The pituitary gland is a pea-sized endocrine gland located at the base of the brain, in a bony cavity called sella turcica, attached to the hypothalamus by a stalk (infundibulum). It is divided into anterior and posterior pituitary, secreting hormones that regulate growth, reproduction, metabolism, and other endocrine glands. Thus, it's in the head, not neck or abdomen.

Explanation:
The plasma membrane is selectively permeable, regulating the entry and exit of specific molecules into and out of the cell. Lysosomes are membrane-bound organelles containing powerful hydrolytic (digestive) enzymes for intracellular digestion. The nucleolus is the site of ribosomal RNA (rRNA) synthesis and ribosome assembly, not protein synthesis, which occurs at ribosomes. Thus, statements 1 and 3 are correct.