A real image is formed when light rays actually converge to a point in space. Because the rays cross, the image you’d see (or project onto a screen) is inverted relative to the object. This contrasts with a virtual image, which is formed by diverging rays that only appear to originate from a point and cannot be projected, and is usually upright. The focal point is simply where rays converge after reflection or refraction, the optical axis is just the reference line through the system, and a lens is the device that bends the light, not the image itself. So an upside-down image formed where light rays meet is a real image.

Selective breeding is choosing individuals with desirable traits to serve as parents for the next generation. By selecting those organisms that display the traits we want and allowing them to reproduce, those traits are more likely to appear in their offspring, and, over generations, become more common in the population. This is driven by humans, using natural variation that already exists. This differs from hybridization, which involves crossing individuals to combine traits and often involves different varieties or species; cloning, which creates an exact genetic copy of one organism; and genetic engineering, which directly alters genes using laboratory techniques. An example of selective breeding is choosing cows that produce a lot of milk and breeding them to increase milk yield in the herd.

Molecules built from amino acids that become large and functional are proteins. Proteins are polymers formed when many amino acids link together through peptide bonds to create long chains that fold into specific three‑dimensional shapes. Those shapes enable a wide range of jobs in the cell, from speeding up chemical reactions (enzymes) to providing structure (collagen) and carrying substances (hemoglobin). The term here points to a particular kind of polymer that specifically consists of amino acids and has biological roles, which is why protein is the best answer. A general polymer is a large molecule made of repeating units, but it doesn’t name the specific type made from amino acids. A monomer is a single amino acid, not the entire molecule. An ester is a chemical group, not the large biomolecule described.

A pedigree is the diagram that shows how a trait is passed from one generation to the next. In pedigrees, males are usually squares and females are circles; a horizontal line connects spouses, and vertical lines link parents to their offspring across generations. Shading or other marks indicate who has the trait, making it easy to see inheritance patterns, such as whether a trait tends to appear in every generation or skip generations. This focus on inheritance across generations distinguishes it from a general family tree, which maps relationships without emphasizing how traits are transmitted. So the term that fits best is pedigree.