Which of the following statements about the ozone layer is correct? MCQ with Answer and Explanation

Explanation:
Relaxin is a peptide hormone produced by the corpus luteum and the placenta during pregnancy. Its primary roles are to relax the smooth muscles of the uterus (inhibiting contractions to maintain pregnancy) and to soften and increase the flexibility of the connective tissues in the pelvis, specifically the pelvic ligaments and the pubic symphysis. This relaxation and widening of the pelvic joints facilitate the passage of the baby through the birth canal during delivery.

Explanation:
The Krebs cycle (citric acid cycle) occurs in the mitochondrial matrix in eukaryotes. The enzymes for the cycle are soluble in the matrix. The inner membrane houses the electron transport chain and ATP synthase. Cytoplasm is the site of glycolysis, chloroplast stroma is the site of the Calvin cycle. Thus, the matrix is the correct location.

Explanation:
Restriction endonucleases (restriction enzymes) recognize specific palindromic DNA sequences and cleave the phosphodiester bonds, producing sticky or blunt ends. They are essential tools for recombinant DNA technology. DNA polymerase synthesizes DNA, ligase joins fragments, helicase unwinds. Examples: EcoRI, HindIII. These enzymes are naturally present in bacteria as a defense against viruses.