Chapter 3 Flashcards
As water cools below 4°C, it expands and becomes less dense. Why is this beneficial to organisms living in a lake during a cold winter?
The property of water to freeze and become less dense than it was in liquid form is beneficial to organisms living in a lake during a cold winter because it means that the ice on the lake will form from the top down. So there will be an ice layer on top and the organisms under can survive during the cold
Given that heat readily transfers between an organism’s body and water, what would you predict about the temperature of the boundary layer around an animal’s body compared to the temperature of the surrounding water in cold weather?
Because heat constantly moves from warmer to cooler areas, if an organism’s body is warmer than that of the water, heat will move out of the organism and into the water. This means that the boundary layer around the animal’s body will be warmer than the temperature of the surrounding water in cold weather.
Based on the properties of water, why do nonpolar compounds such as fats and oils not dissolve well in water?
They have no net charge so would not float on top of water, they would just not dissolve (do not bond to water molecules like salt ions do)
Some lakes around the world have thick deposits of limestone, which is made up of calcium carbonate, and are resistant to the effects of acid rain. What parallels can you draw between these lakes and the smokestack scrubbers used in coal-powered factories?
These lakes with thick deposits of limestone made up of calcium carbonate are resistant to the effects of acid rain. Smokestack scrubbers used in coal powered factories regulate air pollution by removing harmful particles (such as chemical byproducts and gases) from individual exhaust streams. , it lowers the chance of these substances reacting with other molecules such as water and oxygen to make acid rain. Both mechanisms resisting effects of acid rains is one of the parallels.
Both saltwater and freshwater fish have adaptations to control the movement of water and salts across their external surfaces. Describe what would happen without these adaptations.
If aquatic species have too many solutes absorbed in their bodies, they must free themselves of the excess solutes. If freshwater fish continuously gain water when they consume food they must respond to the influx of water by eliminating excess water thru their urine. Maintaining concentration of salts and water is crucial because solute concentrations can disrupt the functions of cells since they affect how proteins approach with different molecules. Marine animals need osmoregulation to regulate the correct solute balance.
How would the process of natural selection favor the evolution of increased salt tolerance in response to increased use of road salt in cold latitudes that ultimately finds its way into streams and lakes?
Road salts go into streams and lakes when ice is melted. The water as a result is saltier than it initially was and aquatic species become sensitive to their environment. In order to counteract this problem, aquatic species must adapt to high salinity in the water, if they survive then by natural selection and survival of the fittest, offsprings can be born to tolerate high salinity. Then this mutation will be passed on because it’ll be seen as desirable and they will reproduce more offspring.
Using your knowledge of how dissolves and reacts in water, explain why global increases in atmospheric co2 should cause a decrease in the pH of ocean water.
When CO2 dissolves in water most of the molecules combine with water and convert into carbonic acid. Carbonic acid molecules can release hydrogen ions to form either bicarbonate or carbonate ions. The release of hydrogen ions into the water causes a decrease in pH since an increase in hydrogen concentration lowers the pH in water, causing it to become more acidic.
How would countercurrent selection in fish gills be beneficial for an animal trying to get rid of ?
Since too much carbon dioxide can be fatal to animals. As when carbon dioxide is trapped, it reduces the amount of oxygen that reaches the body. Thus, the counter-current selection mechanism can be beneficial for an animal trying to get rid of CO2. countercurrent selection in fish gills allows for more O2 and CO2 being diffused out.
How does thermal pollution relate to the concepts of thermal optimum and critical maximum temperature?
The physiology of aquatic organisms has been selected over time so that these animals can achieve peak performance at the ambient temperatures of their surroundings. For example, fish that live in lakes with water temperature 20 degrees celsius, they tend to swim fastest in that 20 degrees. If the lake temperature is changed by thermal pollution , such as by discharge of water from a power plant, the fish suffer lower fitness because of the warming of the lake.
If the algae that live in corals need as a carbon source for photosynthesis, why do scientists argue that global increases in CO2 are playing a role in the decline in coral reefs around the world?
Since CO2 is in equilibrium with dissolved CO2 in the ocean, the recent increase in atmospheric CO2 caused an increase in dissolved CO2 which results in ocean acidification. Carbonic acid dissociates to bicarbonate ions and hydrogen ions, and combining hydrogen and carbonate ions makes up bicarbonate. This leads to carbonate ions being made less available for corals to create their exoskeleton of calcium carbonate. The decline in pH can also dissolve the calcium carbonate skeletons of the coral.
As oceans absorb carbon dioxide (CO2), they become more acidic. This affects the ability of reef-building corals to grow their skeletons and form the foundation for coral reefs.
