Which of the following is an example of a unicellular organism? MCQ with Answer and Explanation

Explanation:
Fertilization in humans typically occurs in the fallopian tube (ampullary region), not the uterus; the zygote then travels to the uterus for implantation. The placenta is the vital organ providing oxygen and nutrients to the growing fetus and removing waste. Spermatogenesis, the production of sperm, occurs in the seminiferous tubules of the testes. Thus, statements 2 and 3 are correct.

Explanation:
Insulin lowers blood glucose by promoting cellular uptake and glycogen synthesis, opposing glucagon which raises glucose. Cortisol and epinephrine are counter-regulatory hormones that increase blood glucose.

Explanation:
Smooth endoplasmic reticulum (SER) lacks ribosomes and is involved in lipid and steroid hormone synthesis, carbohydrate metabolism, and detoxification of drugs and poisons (via cytochrome P450 enzymes). Rough ER synthesizes proteins. Golgi modifies/packages. Lysosomes digest. Liver cells have abundant SER. SER also sequesters Ca²⁺ ions in muscle cells (sarcoplasmic reticulum).