Factors that Delay Reproduction of a Plant and How They are Actually Helpful to the Plant Species.

A perfectly healthy seed may not germinate for a long time; months, or possibly even years.  There are multiple factors that determine the timing of germiantion.  Through the beginning of the life cycle of a plant; the period between pollination to germination, there are several factors that essentially slow down, or delay the reproduction process of a plant.  Most of these factors, that slow or delay the process, are actually helpful to the plant species.

How do these delaying factors actually help the seed?  Seed germination requirements essentially help the seed grow under ideal conditions.  The seed does not usually germinate until the conditions meet the requirements.

One of the biggest factors that delays seed germination is season.  There are different plant species that can thrive in the different seasons throughout the year, however, one given plant species that thrives in spring may not be able to survive through winter. This factor slows the germination of a seed, and if the seed somehow germinates anyway, the chance of survival is low.  The limitations of the seasons are ultimately beneficial to the plant species.

Another significant germination-delaying factor is food/water supply.  If there is not enough nutrition in the environment, the plant will struggle, and may not survive, thus this is an important limiting factor.  Germination should not happen if there is not a stable food supply.  If there is lack of water in the environment, like nutrition, the plant has a low risk of survival.  However, unlike nutrition, too much water can also be harmful to the plant species and can effect the timing of germination.

These are a small few of the many factors that delay or slow down the germination of a seed, there are many more factors that play an equally important role.

How the Calvin cycle indirectly depends on light.

Photosynthesis is the process through which plants (and some other organisms), covert light energy from the sun into chemical energy that can be utilized by other organisms.  In order to carry out this complex process, cells are equip with specialized cells.  There is a cell wall made of cellulose, within, there are membrane closed organelles, and in addition, there is another specialized organelle called a chloroplast.  The chloroplast is the feature of the plant cell  that allows the plant to carry out photosynthesis.

In photosynthesis, there are two major stages, the first being light-dependent reactions and the other being the Calvin cycle, both take place within the chloroplast.  The light dependent reactions occur before the Calvin cycle takes place.  While the Calvin cycle is not actually part of the light-dependent reactions of photosynthesis, the Calvin cycle does indirectly depend on light.

The light-dependent reactions, as stated above, occur prior to the Calvin cycle.  The Calvin cycle actually requires the use of the products from the light dependent reactions.  Products include ATP (adenosine triphosphate), NADPH (nicotinamide adenine dinucleotide phosphate-oxidase), and also o2 that is released into the atmosphere.  There are energy and material requirements of the Calvin cycle, which rely on light-dependent reactions as their suppliers.

There are 3 phases of the Calvin cycle: carbon fixation, reduction, regeneration of co2 acceptor.  With all three phases, there is an overall “cost” of the Calvin cycle.  The Calvin cycle needs outside resources, these resources are produced by the light-dependent reactions.  These “costs” of resources include, 3 co2, 9 ATP, and 6 NADPH.  Co2 comes from the atmosphere, however, without light-dependent reactions, the Calvin cycle has no way to obtain the required ATP and NADPH.

The Calvin cycle is indirectly dependent on light because without the light-dependent reactions, and their products, the Calvin cycle cannot take place.

The challenges of Taxonomy. Is Taxonomy necessary?

Taxonomy is the science of naming and classifying living organisms.  Systematics are the use of data to determine the relationships between different species.  Systematics guide the process of taxonomy, which classify all the living organisms. This is a complex process due to the fact that there are so many living organisms in the world’s overall biomass.

In early taxonomy, there were two kingdoms in which organisms were classified: plants, and animals.  However, there were organisms that possessed characteristics of both plants and animals.  This kingdom of two, was later expanded to include protists, (organisms that possessed the characteristics of animals and plants).  However, this did not include a category for every living organism.  Thus 5 animal kingdoms were developed: plants, animals, fungi, protists, and monera.

Monera, which the single celled prokaryotic classification,posed an issue.  Prokaryotic cells are more similar to eukaryotic cells, than to other prokaryotic cells.  For this and other reasons, monera has become obsolete.

These kingdoms are divided into three domains: bacteria, archaic, and Eukaryota.  (Monera possesses characteristics of more than one domain; another reason why it is obsolete.)

This system has flaws and errors, but at this point, it is the only method scientists have been able to use, somewhat effectively.  A biologist’s classification should not necessarily be taken as an absolute inviolable truth, because there are still many errors in the system.  A biologist’s classification should be considered and also analyzed, with an open-critical mind.

For now, this system is both necessary and important.  Systematics and taxonomy have flaws, but they are an essential means of organization.  This system makes the work of a biologist easier, when researching, or discovering a new species.  Perhaps a better method, with more accuracy will eventually be developed, but for now, biologist’s rely on systematics and taxonomy.

The Impacts of Mutualism, Predation, and Interspecific Competition.

Explain how mutualism, predation, and inter-specific competition are different from each other. How does each one affect the interacting populations of the two species?

Mutualism, predation, and inter-specific competition, are all categorized as inter-specific interactions between two species.  Each one of these include an interaction between two or more species in the same environment.  In each of these interactions, each species is either harmed or benefited by the type of interaction.

  1. Mutualism is when two organisms work together in a way that is beneficial (or maybe even essential) for both parties.  An example of this is the relationship between bumblebees and flowers.  The bumblebee collects nectar, which is the essential source from which the bumblebee makes their food.  In the process of collecting nectar, the bee flies from flower to flower spreading pollen, helping the flowers in an area to pollinate, which is essential process for the reproduction of the flower.  This is an interaction between two species in which both species benefit.
  2. Predation is the involvement of two organisms, when one species (the predator) kills and eats another species (the prey) that is subordinate on the food chain.  An example of this is a coyote, catching and feeding on a rabbit.  The coyote needs the nutrition of the rabbit, it is essential for survival.  If there were not predators such as coyotes to prey on rabbits, the rabbit population would expand to an unmanageable number.  The predator benefits from this interaction at the expense of the prey, who only receives harm, or in this case, death.
  3. Inter-specific competition is when two different species compete for the same resource in a given ecosystem.  Predators, herbivores, and any type of plant encounter this issue.  An example is when the main diet of a hawk in a given ecosystem is a rabbit, but coyotes in that same ecosystem are supported by rabbits.  Both have a limited supply due to the pressure on the rabbit population caused by both species.  Neither species really benefits from this.

Savanna vs. Tropical rain forest.

From Wikipedia, “A biome /ˈbm/ is a community of plants and animals that have common characteristics for the environment they exist in.”  There are two categories of biomes, terrestrial biomes and aquatic biomes.  In these two general categories there is a wide variety of biomes.  In this assignment, I have selected, and will contrast two terrestrial biomes: the savanna, and the tropical rain forest.

A savanna is an open grassland, the trees in a savanna are sufficiently spread so that they do not create a canopy blocking direct sunlight to the soil.  However, this does not mean that they do not have high tree density, the trees are simply more regularly spaced than in tropical  forests.  Savanna covers about 20% of the earth’s surface, and despite the dryness, the savanna can support a lot of life.  Grazing or browsing animals are common inhabitants of a savanna.  The temperature year-round generally averages in the high 70’s (68-86 F), which is helpful to the organisms living there.  One of the challenges that faces the inhabitants of a savanna, is the danger of wildfires, which are common in a savanna.

Unlike the savanna, tropical rain forests have a canopy of trees that almost entirely blocks direct sunlight to the soil, this provides opportunity for organisms very different from those who occupy a savanna.  Tropical rain forests do not encounter a dry season, and encounter a lot of rain (avg. of 60 mm per month) year round.  Tropical rain forests are withing 10 degrees (north or south) of the equator.  The temperature is fairly consistent year round- rarely getting above 93 degrees Fahrenheit, and rarely getting below about 68 degrees Fahrenheit, which is pretty consistent year round, however, not as consistent as the average savanna temperature range.

The two biomes are significantly different from one another and the inhabitants of each face different challenges every day.  The organisms in each biome are equip to survive the conditions of  that biome.

Cancer.

“Is cancer alive? Why aren’t doctors able to uncover a single cause or cure for it? Why isn’t cancer contagious?”

The human body is one big complicated system.  Many genes control different growth factors, and other purposes cells must carry out within this system.  A system this delicate and complicated, surfaces a lot of opportunity for things to go wrong.  Things go wrong when simple mutations occur in these genes, which prevent them from functioning properly.  Oncogenes are cancer causing genes, which are initially caused by simple mutations.

So, is cancer alive?  No, the cancer tumor itself is not alive apart from the living organism.  The tumor is made of abnormal tissues initially caused by mutations of genes that control essential functions of the cell.

Doctors are unable to develop a single cure, because they have not identified the single cause.  Doctors, scientists, and bio-technicians, are getting closer everyday to uncovering and understanding the single cause for cancer.  As of now, it is clear that it is the combination of many different mutations.

Why isn’t cancer contagious? A small percentage of cancers are actually hereditary, however, cancer is not contagious like a flu.  Cancer happens within the organism, caused by several different factors that produce excess proteins and tissues.  It is, in a sense, like a machine that develops minor issues that continue to build and expand and, over time, create a major, and possibly fatal, issue.  Cancer is not a virus that can be spread by contact, but rather, a disease caused by mutations in this complicated system.

Why men are 50% more likely to be colorblind than women.

Joking aside, why are men far more likely than women to be colorblind?

Men are more likely to be colorblind than women, why?  It is all about genes.  Our chromosomes come in pairs, we get one from each parent.  The female gamete has two X chromosomes, and the male gamete has an X and a Y chromosome.  For the child to be female, it must get an X chromosome from the mother, and an X chromosome from the father.  For the child to be male, they must get the X chromosome from the mother and the Y chromosome from the father.  The child will get an X from the female gamete regardless.

The genes for colorblindness are on the X chromosome.  If a female has something wrong with one of her X chromosomes, she has another to back it up, she would thus need two damaged X chromosomes to inherit colorblindness.  Males, however, only have one X chromosome, so if this chromosome is damaged, there is not another one to back it up.  Women have a chance of inheriting colorblindness, however, men are 50% more likely than women to inherit colorblindness.

The growth of an organism explained on a cellular level.

“You are probably taller now than you were 4 years ago. What, specifically, caused you to become taller? Explain what happened on a cellular level.”

The cell is the basic unit of life.  Anything smaller than a cell; unable to perform the jobs of the cell, is not a form of life.  Cells are what larger organisms are made of.  Having the ability to understand life on a cellular level allows us to understand the larger organisms.

In terms of human growth, what happens on a cellular level?  Over a time period of, in this case, 4 years, what happens inside a child’s body that causes them to grow taller?  Cells themselves do not grow beyond a certain point, as they would get so large that the systems inside the cell would no longer function properly.  Think of an infant, if they had the same cells from infancy to adulthood, and the cells just grew, the cells would be incredibly large and unable to function properly.  What happens?  The cells actually duplicate.  The cells split, through a process called mitosis, which creates a genetically identical cell.

There are two different phases of the cell cycle, the mitotic phase which is where mitosis occurs, and the inter-phase, during the times when the cell is just carrying out the job it is designed to do.  The cells know what phase to be in because they receive messages from other cells.  The outer membrane of the cell is covered with receptors, that receive messages that “tell” the receiving cell about other cell activity, and this tells the cell what phase it should be in.  The cells in an organism work together systematically to carry out growth, healing, and many other purposes of the organism.

Proteins vs. Carbohydrates.

Proteins are involved in just about everything a living organism does.  There are many different kinds of proteins, each performing a different series of applications.  Transport proteins serve as transportation in an organism, they get things from one point to another.  The 2 proteins actin and miocin, give the muscle fibers the ability to contract.  Proteins are involved in more than just muscle. Motor proteins move the flagellum in the cilium of a micro organism, such as bacteria.  A majority of motor proteins have the ability to modify their shape in a series of repeatable ways and this is where motion comes from.  These few tasks, along with the tasks of the other 10’s of millions of different kinds of proteins happen on a molecular scale inside the smallest form of life, the cell.

Carbohydrates also play a crucial role in every organism.  A carbohydrate is a molecule consisting 3 different atoms: carbon, hydrogen, and oxygen.  Carbohydrates, along with fats, store energy (calories) for an organism.  It is crucial that living organisms have this means of storing potential energy.

While proteins and carbohydrates perform completely different tasks, they are both essential to all living organisms.