Consider the following statements about the heart: 1. The SA node is the natural pacemaker. 2. The AV node delays the impulse before it passes to ventricles. 3. The Purkinje fibers conduct impulses through the ventricular walls. Which of the above is/are correct? MCQ with Answer and Explanation

Explanation:
Alveoli are tiny, thin-walled air sacs surrounded by a network of pulmonary capillaries. Oxygen diffuses from alveolar air into blood, and CO₂ diffuses from blood into alveolar air. Bronchi and bronchioles are air passages, trachea is the windpipe. The large surface area of alveoli (about 70 m²) facilitates efficient gas exchange.

Explanation:
Fungi are eukaryotic, mostly multicellular (except yeast), and are heterotrophic by absorption (saprophytic or parasitic). Their cell walls contain chitin. Monera are prokaryotic, Protista are unicellular eukaryotes, Plantae are autotrophic multicellular organisms. Fungi play key roles as decomposers in ecosystems.

Explanation:
During telophase, the chromatids reach the poles, decondense, and the nuclear envelope reassembles around each set, forming two daughter nuclei. The spindle disappears. Prophase involves nuclear envelope breakdown, metaphase aligns chromosomes, and anaphase separates chromatids. Cytokinesis often overlaps with telophase, dividing the cytoplasm.