A sentry is someone who stands guard over something, to protect it. The sentry in this picture is guarding the entry to the Tower of London, which contains the Queen's jewels.
Sepia is a pigment made from cuttlefish ink. It can be used to draw or paint with. Anything that looks like it is made from sepia ink is also called sepia, for example a photograph that has been made into monochrome in browns.
Scientific name: leptailurus serval
Sis forSesame seeds
Scientific name: sesamum indicum
Sesame seeds are the seeds of a plant from Africa and India that grows to about a metre high. The seeds can be pressed to extract the oil but are used most often sprinkled on other foods as a flavour and garnish. You often see them stuck to the top of loaves of bread.
The sesame seeds in the picture are on top of some cooked spinach.