30. Spore

A spore is a haploid reproductive cell, usually unicellular, capable of developing into an adult without fusion of another cell. In this picture, the middle part of the flower contains the spores used for asexual reproduction.

29. Calvin Cycle

The Calvin cycle (or Calvin-Benson-Bassham cycle) is a series of biochemical reactions that take place in the stroma of chloroplasts in photosynthetic organisms. In this picture, you can see the dark spots or dark reactions of C3 photsynthesis on these leaves.

28. Parasitism

Parasitism is a living arrangement in which an organism lives on or in an organism of a different species and derives nutrients from it. In this picture, a fly feeds off of the microorganisms on this piece of dog feces.

27. Tropism

Tropism is a response to an external stimulus. This plant has the tendency to move towards a specific target (the sun). You can tell that it is growing more towards the left where the sun shines through the window.

26. Lipids for Storing Energy

Lipids are any group of organic compounds including the fats, oils, waxes, sterols, nucleic acids, and triglycerides. Lipids are characterized by being insoluble in water, and account for most of the fat present in the human body. This picture displays a person and one of the "fatty" parts of the body.