Aggregate Fruit

This is a picture of a raspberry. A raspberry is an example of an aggregate fruit. Aggregate fruits develop from a flower containing more than one separate carpel, or several ovaries. When these carpels mature, they cluster together to form a single receptacle, the aggregate fruit. In contrast, a simple fruit develops from a single carpel. Examples of aggregate fruits include raspberries, blackberries, and strawberries.

Osmosis

This is a picture of water. Plants rely on the nutrients and water in soil to survive. In order for water uptake to occur, plants undergo a process called osmosis. By definition, osmosis is the diffusion of free water, which is not bound to any solutes or surfaces, across a membrane. This diffusion moves water molecules from a place of higher concentration to a place of lower concentration so that a stable state of equilibrium is made. For example, when a plant cell is set in a solution that has a higher water concentration/pressure, water will move into the cell. The growth of a plant cell is primarily dependent on water uptake. Furthermore, osmosis is a function vital to plant stability. It distributes water through selectively permeable membranes to maintain proper volume and pressure of all plant cells.

Phototropism

This is a picture of a leaning plant. This plant has been affected by phototropism. Tropism is a growth response that results in plant organs leaning towards or away from any stimuli. In phototropism, the stimuli is light. The shoots of plants usually result in positive phototropism (towards the light), while the roots generally result in negative phototropism (away from the light). The cells on the plant that are farthest from the light contain a hormone chemical, auxin, that reacts when phototropism occurs. This causes the cells on the darker side of the plant to elongate faster than the cells on the brighter side, resulting in a leaning appearance. Phototropism is most often observed in plants, but can also occur in other organisms, such as fungi.

Mesophyll

This is a picture of a leaf. Mesophyll is the inner tissue of a leaf. It is the middle layer between the upper and lower epidermal layers. The mesophyll layer is composed of parenchyma, or photosynthetic cells with chlorophyll, which explains why it is the site of photosynthesis in leaves. The mesophyll itself is also split into two layers, including palisade mesophyll and spongy mesophyll. The palisade mesophyll layer is the upper part of the mesophyll layer and consists of tightly packed parenchyma cells that function to trap sunlight. In the spongy mesophyll, the cells are more loosely arranged, so that air spaces allow for gas exchange. With the occurrence of photosynthesis, the mesophyll layer is usually filled with gases, including carbon dioxide and oxygen.

Bottleneck Effect

This is a picture of beads in a bottle being poured out. The beads in the bottle represent a population an its gene pool. The beads remaining in the bottle represent the population and its gene pool remaining after a sudden event in the environment, such as a flood. This drastic reduction in population size due to an environmental event can cause the bottleneck effect. By chance, some alleles may be overrepresented, underrepresented, or even completely absent in the remaining population gene pool. In other words, a bottleneck can significantly reduce a populations genetic variation. Reduced genetic variation means that the population may not be able to adapt to new selection pressures, because the genetic variation that selection would act on may be out of the population. After a bottleneck effect, genetic drift will most likely have these effects on the gene pool until the population becomes large enough so that chance events have less of an impact.  

Artificial Selection

This is a picture of broccoli. Broccoli has been cultivated from wild mustard through artificial selection. Artificial selection is a selection process in which evolution can occur. Humans have modified species, since before Darwin and Wallace, over many generations by selecting and breeding individuals that possess desired traits. An example is with how farmers and breeders have caused evolution in farm stock by only allowing plants and animals with desirable characteristics to reproduce. This process is called artificial selection because people, instead of nature, select which organisms are "better suited" to survive and reproduce.

Gene

This is a picture of an eye, featuring its blue coloration. Eye color is an example of a phenotype, or physical characteristic, determined by genes. A gene is a unit of heredity that is passed from parent to offspring. It is a specific locus, or location, on a strand of DNA, in which the nucleotide sequencing encodes a functional RNA or protein product. Protein synthesis is what determines physical characteristics. Most biological traits are influenced by polygenes, or many different genes.