The correction option is B. The plants that belong to phyllum anthophyta are heterosporous, that is, they produce both male and female reproductive organs separately. Fruits grow when the male gamete fertilizes the female ovary. Their fruits are always fleshy with seeds inside them. A good example of a plant that belong to this phylum is pawpaw.
Protein structure is the three-dimensional arrangement of atoms in a protein molecule. Proteins are polymers — specifically polypeptides — formed from sequences of amino acids, the monomers of the polymer. A single amino acid monomer may also be called a residue (chemistry) indicating a repeating unit of a polymer. Proteins form by amino acids undergoing condensation reactions, in which the amino acids lose one water molecule per reaction in order to attach to one another with a peptide bond. By convention, a chain under 30 amino acids is often identified as a peptide, rather than a protein.[1] To be able to perform their biological function, proteins fold into one or more specific spatial conformations driven by a number of non-covalent interactions such as hydrogen bonding, ionic interactions, Van der Waals forces, and hydrophobic packing. To understand the functions of proteins at a molecular level, it is often necessary to determine their three-dimensional structure. This is the topic of the scientific field of structural biology, which employs techniques such as X-ray crystallography, NMR spectroscopy, and dual polarisation interferometry to determine the structure of proteins.
Protein structures range in size from tens to several thousand amino acids.[2] By physical size, proteins are classified as nanoparticles, between 1–100 nm. Very large aggregates can be formed from protein subunits. For example, many thousands of actin molecules assemble into a microfilament.
A protein may undergo reversible structural changes in performing its biological function. The alternative structures of the same protein are referred to as different conformational isomers, or simply, conformations, and transitions between them are called conformational changes.
Answer:
The correct answer is - tight junctions.
Explanation:
Tight junctions are one of the cell-cell junctions that make a barrier to the passage of material which is a present in epithelia. This barrier is impermeable to most of the materials with soluble molecules. This barrier is made up of the occludin and claudin proteins.
Tight epithelia have tight junctions and examples of such junctions are the distal convoluted tubule or DCT, and the collecting duct of the nephron in the kidney.
Thus, the correct answer is - tight junctions.
