The process that moves food through the esophagus by rhythmic contractions is: MCQ with Answer and Explanation

Explanation:
In plant tissue culture, when an explant (a piece of plant tissue) is placed on a nutrient medium containing specific plant hormones (like auxins and cytokinins), the cells dedifferentiate and undergo rapid, unorganized division to form a mass of cells called a callus. This callus is undifferentiated. Under appropriate hormonal conditions, this callus can then be induced to redifferentiate and form organized structures like shoots and roots (organogenesis) or somatic embryos.

Explanation:
The placenta begins to form immediately after implantation of the blastocyst. By the end of the first trimester (around 12 weeks of gestation), the placenta is fully formed and takes over the primary role of hormone production (progesterone and estrogen) from the corpus luteum. It is fully functional in providing oxygen, nutrients, and waste removal for the developing fetus for the remainder of the pregnancy. It is not fully formed at conception, nor does it wait until the second or third trimester.

Explanation:
Saccharomyces cerevisiae, commonly called baker's yeast, ferments sugars to produce CO₂ and ethanol. The CO₂ causes dough to rise, giving bread its porous texture. Lactobacillus is used in yogurt and cheese making, Aspergillus niger in citric acid production, Streptococcus in some dairy ferments. Yeast is a unicellular fungus. Fermentation is an anaerobic process. Alcohol evaporates during baking.