Biology 1M03 Exam - McMaster Questions & Answers Latest Updated

What is the carbon cycle? Why is it important? - Answer The carbon cycle is the mouvement of carbon between species, the earth, the atmosphere and oceans. Without carbon, ecosystems would not function and persist over time. Most exchanges involve the ocean. What are the crucial processes in the carbon cycle? Why are they important? - Answer Cellular respiration and photosynthesis. They cancel each other out so that there isn't too little CO2 (causing a frozen earth) or too much CO2 (causing an increase in the temperature of the earth). What is the Keeling curve? - Answer The Keeling curve records changing levels of carbon dioxide in the atmosphere over time. Variation within a year = seasons Variation within years = global warming Extending time scale says more about the global ecosystem than annual CO2 values Are variation in the carbon cycle normal? - Answer Human activities play an important role in the modern carbon cycle Variation in levels of CO2 are normal, however when the variation becomes too big, then there is an unusual change. Carbon isotopes show that much of the CO2 added to air over the past 70 years comes from burning fossil fuels. How do we know that humans add CO2? - Answer The isotopic composition of atmospheric carbon stock. We (and plants) release a signature isotope, 13C Explain the relation between food webs and trophic pyramids - Answer Energy and carbon is transferred through ecosystems/food webs. There's an inefficient energy transfer between trophic levels, 10% of biomass is passed on. Why are the energy transfers between trophic levels inefficient? - Answer Energy leaves the organisms through heat What is the relationship between the nitrogen cycle and the carbon cycle? - Answer Nitrogen influences producers which influences the carbon cycle (producers are the first in the trophic levels, energy/glucose contains carbon) Link the molecule with where its most found in its respective cycle: carbon, nitrogen, phosphorous air, water, rocks - Answer carbon = water/ocean nitrogen = air phosphorous = rocks What is the relationship between biological diversity and primary production? How does the carbon cycle fit into all of this? - Answer The more biological diversity, the more primary production. If it affects the primary production, then it affects the carbon cycle indirectly because its the root of the trophic levels. Can you imagine consequences of losing the top predator? What does this mean to conservation of nature? - Answer Cascade of effects; overpopulation etc. Can you hypothesize how carbon could move (be recycled) two billion years ago? What would be necessary? - Answer Other process not know about, since the nitrogen cycle is intertwined with carbon cycles. Other types of primary and secondary consumers... A mix of adaptations of the organisms What determines the earth's surface temperature? - Answer The principal determinant of Earth's surface temperature is the angle at which solar radiation strikes the surface. It explains why its hotter at the equator and colder at the poles. The tilt also affects the variation in seasons depending on where you are (ex: hotter in june in Canada vs hotter in december in brazil) How is heat transported toward the poles? Why is this distribution important? - Answer Heat is transported toward the poles by wind and ocean currents. It governs the global distribution of rainfall. How does the rotation of the earth affect the wind? - Answer Because of earths counterclockwise rotation about its axis, winds in the northern hemisphere deflect to the right; those in the southern hemisphere deflect to the left. This also affect ocean currents What is the shadow effect? - Answer Shadow effect: mountains imposing regional effects on rainfall patterns. The water from rainfall is carried by the wind till the top of the mountain, that's why its usually moist at the top of them. The other side of the mountain has then no rain and becomes really hot. What are the main contributing factors of biomes? How? - Answer Temperature + precipitations. Mainly because they affect plants. Temperature allows for certain plants to grow, others to die. Precipitations: The rate of evapotranspiration (evaporation from soil and transpiration from plants) affects the rate of precipitation, this is part of the water cycle. What is the relationship between water and land? How does this affect the biomes? - Answer The more water there is, the less land. If there is less land, then there are less producers, meaning that less heat will be lost between species/less heat will be in the atmosphere affecting the temperature of the biomes. How are precipitation and evapotranspiration linked? How does this concern plants? - Answer Positive correlation. Plants evolved independently (convergent evolution) to adapt to the demands (or lack of demands) of their atmosphere. What do these biomes have in common? What differentiates them? Desert and chaparral - Answer Similarity: Both are characterized by arid conditions and low precipitation. Differentiation: Chaparral tends to have a Mediterranean climate with cooler temperatures compared to deserts. Chaparral also often experiences periodic wildfires. Chaparral = Greece Desert = Saudi What do these biomes have in common? What differentiates them? Savanna and Tropical Rainforest - Answer Similarity: Both have warm temperatures and relatively high precipitation. Differentiation: Savannas are characterized by a mix of grassland and scattered trees, while tropical rainforests are dense and lush with a more complex canopy structure. Savanna: Australia Tropical Rainforest: Brazil What do these biomes have in common? What differentiates them? Temperate Coniferous Forest and Taiga - Answer Similarity: Both are characterized by coniferous trees and cold climates. Differentiation: The taiga is a subtype of temperate coniferous forest, specifically referring to the extensive coniferous forests in subarctic regions. Taiga: Quebec Temperate Coniferous Forest: British-Columbia What do these biomes have in common? What differentiates them? Deciduous Forest and Temperate Grassland - Answer Similarity: Both are found in temperate regions with distinct seasons.