Which of the following statements is correct regarding cell theory? MCQ with Answer and Explanation

Explanation:
In angiosperms, the pollen tube must enter the ovule to deliver the male gametes to the embryo sac. The most common and typical pathway is through the micropyle (the small opening at the tip of the integuments), which is called porogamy. In some plants (like Casuarina, Juglans), the pollen tube enters through the chalaza (the base of the nucellus), which is called chalazogamy. Entry through the integuments is called mesogamy. Apogamy is the formation of a sporophyte without fertilization.

Explanation:
Alexander Fleming accidentally discovered penicillin in 1928 when a mold (Penicillium) inhibited bacterial growth on a plate. Florey and Chain purified it.

Explanation:
Bacteria lack a true nucleus; their circular chromosome is concentrated in a region called the nucleoid. Plasmids are extra-chromosomal DNA but the main genome is in the nucleoid. Eukaryotes have a membrane-bound nucleus.