Big Idea 2

 1. Adhesion of Water: Adhesion of water refers to the attraction of water to other polar substances due to hydrogen bonding. The partial negative charge of the oxygen atom and the partial positive charges of the two hydrogen atoms in water molecules allows for this bonding with other polar molecules. Therefore, adhesion makes water "stick" to other polar molecules. On this plant, water droplets are counteracting the forces of gravity by "sticking," or adhering, to the leaves, meaning that something polar on the leaves is hydrogen bonding with the water molecules.

 4. Autotroph: Autotrophs are organisms that are capable of synthesizing organic compounds from simple inorganic substances by using light or chemical energy. Grass is an autotroph because it is able to produce its own food and thus energy from carbon dioxide and water through the process of photosynthesis.

6. Carbohydrate: Carbohydrates are organic compounds that contain carbon, hydrogen, and oxygen in the ratio 1:2:1 respectively. They serve as major energy sources. The simplest of carbohydrates are the monosaccharides, or simple sugars, which include glucose, fructose, and galactose. A potato is high in starch, which is a polymer of many hundreds of both branched (amylopectin) and unbranched (amylose) glucose molecules. 

8. Cellulose: Cellulose is an insoluble, structural polysaccharide that consists of repeated ß-glucose molecules linked in unbranched chains. The cells of this Boxwood shrub, like all other plants, contain cell walls made primarily of cellulose. Humans can not digest cellulose; however, because of symbiotic bacteria and protists in their digestive tract, cows are in fact able to break down cellulose and thus access the rich energy within the compound's bonds.  

10. Cohesion of Water: Cohesion of water refers to the fact that water molecules are attracted to each other due to the partial negative charge of the highly electronegative Oxygen atom and the partially positive charge of the two Hydrogen atoms. Hydrogen bonds form between the Hydrogen atoms of one water molecule and the Oxygen atom of another particularly at the surface of a body of water, and this creates something called surface tension. Surface tension caused by the cohesive forces of water is what allows this leaf to float.

12. Ectothermy: Ectotherms, or "cold-blooded" animals, are organisms whose body temperatures change with the temperature of their surroundings. Ectotherms rely on external sources of heat and cold in order to change their body temperatures when necessary. All amphibians are ectothermic, and thus this poison dart frog is an example of ectothermy because it regulates its body temperature by exchanging heat with its surroundings. 

13. Endothermy: Endotherms, or "warm-blooded" animals, maintain their body temperature above the temperature of the external environment. Unlike ectotherms, they do not depend on the environment for internal temperature regulation. Lemurs are mammals,which are endotherms, and thus they are able to regulate their own body temperature at a favorable temperature by the heat released from internal metabolic processes. 

14. Entropy: Entropy refers to the amount of disorder, or energy unable to do work, in a particular system. Leaves falling in a random and scattered formation on the ground from their fixed and orderly attachments to trees represents an increase in disorder in the system and thus a decrease in the overall free energy. 

15. Enzyme: An enzyme is a substance produced by a living organism that speeds up chemical reactions by decreasing the amount of activation energy required for a particular reaction. Saliva contains many enzymes for both dietary purposes as well as defense purposes. For example, amylase, an enzyme the initiates the breakdown of starch into sugars, is found in saliva. Lysozyme, another enzyme found in saliva, catalyzes the breakdown of bacterial cell walls, in order to inhibit bacterial growth in the mouth cavity. 

16. Fermentation: Fermentation is the anaerobic extraction of energy from sugar by converting it into acids, gases, or alcohol. Yeast obtain energy through fermentation in the presence of sugar by converting the sugar into carbon dioxide and ethanol. This "recycles" the electron carriers in the cellular respiration pathway so that they can be used again in glycolysis to produce more energy as long as sugar is still present. Beer, wine, and liquor are made by the process of ethanol fermentation; however, these substances can only naturally reach a level of 12% ethanol before the yeast starts to die.

19. Heterotroph: A heterotroph is an organism that cannot derive energy from organic matter created by the process of photosynthesis, and so it must feed on plants or animals in order to obtain chemical energy from their organic matter. A lion is a animal that consumes various external sources of organic matter, particularly large mammals such as antelopes, buffalos, and zebras in the wild, in order to acquire energy, and thus a lion is a heterotroph. 

23. Hydrophilic: Hydrophilic, or "water loving," substances are substances that have an affinity for water because they are polar or charged. Sodium chloride (NaCl), an ionic compound, is hydrophilic because of the ability of its individual charged ions to form hydrogen bonds with water molecules. Moreover, because NaCl is hydrophilic, it is soluble in water. 

24. Hydrophobic: Hydrophobic, or "water-fearing," substances are nonpolar substances that have no affinity for water. Olive oil, an unsaturated fat, is a nonpolar molecule due to its very high proportion of nonpolar carbon-hydrogen bonds. Though it has some hydrophilic groups, olive oil is not soluble in water because of its dominantly hydrophobic fatty acid chains. When placed in water, olive oil spontaneously clusters together into droplets because only the glycerol backbones of the fat molecules can form hydrogen bonds with water. The fatty acid chains aggregate away from the water due to hydrophobic exclusion in order to increase the hydrogen bonding potential of the water molecules. 

28. Lactic Acid: Lactic acid (C3H6O3) is a syrupy organic chemical compound produced in the absence of oxygen when pyruvate is directly reduced during fermentation in order to recycle the electron carriers for glycolysis. This kind of fermentation is known as lactic acid fermentation, which is the process by which sugar is converted into energy and lactic acid. Yogurt is produced by the lactic acid fermentation of milk by harmless bacteria, thus lowering its pH and causing it to congeal. 

29. Long-day Plant: A long-day plant is a plant that requires a short night and a long amount of exposure to light in order to flower. Long-day plants grow in the summer when days can last up to twelve hours or more. Spinach is a long-day plant because it will initiate blooming when the day length is thirteen hours or more. 

30. Phloem: The phloem is a tissue in vascular plants that transports photosynthetic food materials from the leaves to other parts of the plant. The veins are the vascular tissue of the leaf, and thus the phloem can be observed in the leaves of this ivy plant.

 32. Saturated Fat: A saturated fat is a fat in which the fatty acid chains have no single bonds between the carbons, and thus they are saturated with the maximum number of hydrogen atoms. The lack of double bonds in the fatty acids of saturated fats causes the fatty acids to align closely and to form a solid at room temperature. Animal meat, such as this piece of prime rib from a cow, contains solid saturated fat at room temperature.

33. Stomata: Stomata are the miniscule openings in the epidermis of the leaves and stems of plants. They are surrounded by guard cells, which regulate their opening and closing, and they allow for gas exchange. Stomata are usually located on the underside of leaves, away from direct contact with sunlight, in order to preserve water when they open to let carbon dioxide in and oxygen out for photosynthesis. The leaves of this rhododendron plant, like the leaves of most vascular plants, contain stomata on their undersides.

37. Unsaturated Fat: An unsaturated fat is a fat in which one or more of the fatty acid chains has one or more double bonds between the internal carbons and thus contains less than the maximum number of hydrogen atoms. Almonds are high in monounsaturated fats, meaning that there is only one double bond in the fatty acid chains of their fat molecules.

38. Xylem: The xylem is a tissue in vascular plants that carries water and nutrients upwards from the roots to the rest of the plant body. The xylem also functions in structure and support. Because bamboo is a vascular plant, it contains a xylem to carry water and nutrients up its tall and narrow stalk.