Who was the first scientist to view live sperm cells and bacteria under a microscope? MCQ with Answer and Explanation

Explanation:
Vascular cryptogams are plants that possess vascular tissues (xylem and phloem) but reproduce via spores rather than seeds. Pteridophytes, such as Selaginella (spike moss), ferns, and Equisetum, fit this description. Funaria and Marchantia are bryophytes (non-vascular cryptogams), and Pinus is a gymnosperm (a vascular phanerogam or seed-producing plant).

Explanation:
Immunoglobulin A (IgA) is the primary antibody found in mucosal secretions, including saliva, tears, nasal secretions, breast milk (colostrum), and the respiratory and gastrointestinal tracts. It plays a crucial role in mucosal immunity by preventing the attachment of pathogens to epithelial cells, a process known as immune exclusion. IgG is the most abundant in blood, IgM is the first to be produced in an infection, and IgE is involved in allergies.

Explanation:
Eukaryotic ribosomes are 80S and composed of a small 40S subunit and a large 60S subunit. Prokaryotic ribosomes are 70S with 30S and 50S subunits. The S (Svedberg) value is a measure of sedimentation rate, not simply additive. Both ribosome types synthesize proteins, but the structural difference allows selective antibiotic targeting (e.g., streptomycin acts on 70S).