Week #5 - Biomes and ecosystems

Question 1

Distinguish between organic and inorganic compounds.

Answer 1

Organic and inorganic compounds are both common and present in biomes and ecosystems. What distinguishes organic from inorganic compounds is that organic compounds possess carbon molecules that are either bonded to another carbon molecule or a hydrogen molecule whereas inorganic compounds lacks this bond in its molecular structure. Another distinctive difference between organic and inorganic compounds is that organic compounds tend to be larger and more complex in its molecular structure whereas inorganic compounds tend to be smaller and much simpler in its structure.

Question 2

Identify two major functions of organic compounds and the source for these compounds for both autotrophs and heterotrophs.

Answer 2

Organic compounds are crucial in providing structure for living organisms and energy, like glucose, to ensure survival. Photoautotrophs gain their organic compounds mainly through photosynthesis, wherein they absorb light energy and convert the inorganic nutrients carbon dioxide and water into glucose. Heterotrophs generally obtain organic compounds through the food they ingest or absorb.

Question 3

Define biogeochemical cycle and outline the main components.

Answer 3

a biogeochemical cycle follows a chemical element as it facilitates through the biotic and abiotic components of an ecosystem again and again, forming a cycle. All biogeochemical cycles must include an nutrient reservoir, as well as producers, consumers, and decomposers.

Question 4

Explain the significance of the elements carbon and nitrogen to living organisms and outline the major
steps in the cycling of these elements in the biosphere.

Answer 4

Nitrogen is a essential building component of amino acids, proteins, and DNA. It is also essential in the production of chlorophyll in plants which allows it to absorb the light energy it needs to perform photosynthesis.

Carbon is essential to all living organisms as it is present in all organic compounds. It makes up carbohydrates, lipids, proteins and nucleic acids. It is also necessary for photosynthetic organisms as it needs carbon to convert it into glucose, giving it the energy it needs to survive.

Question 5

Explain, using examples, the impact humans have made on the carbon cycle.

Answer 5

Deforestation and the burning of fossil fuels cause unnatural disruptions in the carbon cycle. The burning of fossil fuel adds more carbon dioxide, with less trees in the environment, there is a build up of carbon dioxide in the atmosphere as there is not enough trees to take it in. Consequently, it causes other ecological problems such as acid precipitation wherein excess carbon dioxide in the atmosphere reacts with water. As well as rising sea levels, ice caps melting, ocean acidification, and coral bleaching.

Question 6

Explain, using examples, the impact humans have made on the nitrogen cycle.

Answer 6

Agriculture is the main cause of disruption in the nitrogen cycle. It removes nutrients in the ecosystems that would otherwise be cycled back in to the soil. To compensate for the lack of nitrogen, fertilizer is used, but it causes harmful effects to the environment. When plants exceed their critical load, excess nitrogen can contaminate groundwater, freshwater, and marine ecosystems. Sewage runoff causes cultural eutrophication which is excessive nutrient load that promotes harmful algal growth dangerous to freshwater ecosystems.

Question 7

Define trophic level

Answer 7

The trophic level of an organism refers to the feeding
position that it occupies in a food chain or food web in
an ecosystem.

Question 8

Distinguish between food chain and food web

Answer 8

a food chain shows only one potential pathway in the flow of energy from each trophic level to the next whereas a food web shows all potential pathways of energy flow in an ecosystem.

Question 9

Distinguish between grazing food web and detritus food web.

Answer 9

grazing food chain begins from the green plants, which are the principal producers, whereas detritus food chain starts from the dead organic matter or decomposed material, that is usually within the soil. The energy to the grazing food chain comes in sunlight as the autotrophs (green plants) prepare their food (photosynthesis) amid the existence of the sunlight. while, the energy for the detritus food chain is taken in the detritus or the decomposed materials.

Question 10

Explain why food webs have a limited number of trophic levels by referring to the concept
of trophic efficiency.

Answer 10

food webs have a limited number of trophic levels because not all energy is passed off from an initial trophic level to another. energy can sometimes be lost through heat. Furthermore, only an average of about 15% of energy can be converted into new biomass which becomes lesser and lesser the further the food chain goes.

Question 11

Describe a pyramid of energy and explain its shape.

Answer 11

a pyramid of energy is a structure wide at the base and narrow at the top symbolizing the amount of energy available at each trophic level. Its shape illustrates how energy is lost as it flows from each succeeding trophic level to the next.

Question 12

Distinguish between intraspecific and interspecific interactions in a community

Answer 12

Interspecific interactions is the relationships between different species in a community whereas intraspecific interactions is the relationship between same species.

Question 13

predation

Answer 13

Predation refers to interaction where one species, the
predator, kills and eats the other, the prey. An example of predation would be a gazelle that has been feasted upon by a hungry cheetah.

Question 14

herbivory

Answer 14

Herbivory refers to an interaction in which an animal ingests (eats) parts of a plant or alga. It has led to the evolution of plant mechanical defenses (like-thorns) and chemical defenses as well as adaptations by
herbivores to overcome these defenses. An example of herbivory is when a zebra or any type of herbivore feeds off of a plant.

Question 15

competition*

Answer 15

Interspecific competition occurs when 2 or more species
utilize the same resource. Two types:

1. In exploitative competition there is no physical interaction
   but both species are negatively impacted because the
   resource is in short supply.
2. Interference competition involves physical interaction
   which negatively impacts both species. The resource may or
   may not be in short supply.

• Intraspecific competition occurs when members of the same
species utilize a common resource

Question 16

parasitism

Answer 16

one organism, the parasite, derives
nourishment from another organism, its host, which is harmed in the process. Parasitism affects population size and the structure of communities. An example of parasitism are fleas and ticks that live off of the blood of cats and dogs.

Question 17

commensalism

Answer 17

one species benefits and the other is unaffected i.e., it is neither harmed nor does it benefit. An example would be the barnacle and the whale. the barnacle benefits as it is able to partake in the feeding of plankton whenever the whale swims through plankton-rich waters to feed and it is also more protected to a certain degree from predators as it is non-sessile and is attached to a much larger and intimidating organism.

Question 18

mutualism

Answer 18

benefits both species – usually by obtaining nourishment or protection. An example of mutualism is the relationship between the oxpecker and a rhino. The oxpecker lives on the back of a rhino and has a readily available source of bugs which it can eat and the rhino benefits having the bugs off of its back removed.

Question 19

Distinguish between gross primary productivity and net primary productivity.

Answer 19

Gross primary productivity and net primary productivity are both amounts of energy that is present within the primary trophic level of a food chain or web. Gross primary productivity is the total amount of energy present within a certain trophic level whereas net primary productivity is the percentage of energy that can be successfully converted into new biomass by the primary trophic levels’ succeeding trophic level.

Question 20

Ecology

Answer 20

the branch of biology that deals with the relations of organisms to one another and to their physical surroundings.

Question 21

Community

Answer 21

an interacting group of various species in a common location.

Question 22

Ecosystem

Answer 22

A system that includes all living organisms (biotic factors) in an area as well as its physical environment (abiotic factors) functioning together as a unit.

Question 23

Biome

Answer 23

A region of the earth’s surface the relationships between climate, animals, and plants found within it.

Question 24

How does energy flow and nutrients cycle through an ecosystem?

Answer 24

Energy flows from primary producers to primary consumers and so on. It enters as light and exits as heat. Nutrients cycle within an ecosystem beginning at a nutrient reservoir and facilitating through producers, consumers, and decomposes present in the ecosystem.