The animal that has a closed circulatory system is: MCQ with Answer and Explanation

Explanation:
Root hairs are tubular extensions of epidermal cells in the zone of maturation of roots. They increase surface area for absorption of water and minerals. Cortical cells form the ground tissue, endodermis is the innermost layer of cortex with Casparian strip, and pericycle gives rise to lateral roots. Root hairs are unicellular in angiosperms, living for a short period and constantly replaced.

Explanation:
DNA ligase seals the phosphodiester bonds between adjacent DNA fragments, joining them together. In recombinant DNA technology, it is used to ligate the gene of interest into a vector. Restriction enzymes cut DNA, DNA polymerase synthesizes DNA, and helicase unwinds the double helix. Ligase is essential for finalizing the recombinant DNA molecule.

Explanation:
Immunohistochemistry (IHC) uses enzyme- or fluorophore-linked antibodies to visualize specific antigens in tissue sections. ELISA is for liquid samples, Western blot for membrane, flow cytometry for cells.