Biology 221 Notes Exam I. Powerpoint 1. Biolog y is the study of life. There are currently millions of extant (living) species (see below for taxonomic levels). Properties that are shared by all living organisms. Order.
There are currently millions of extant (living) species (see below for taxonomic levels)
Each organism possesses a highly ordered structure even if they may seem simplistic (like prokaryotic cells or single-celled eukaryotic organisms).
All reproduce and pass their DNA from parent to offspring. DNA then directs the pattern of growth and development.
All organisms respond to internal and external stimuli.
All living organisms obtain and then transform energy into a usable form (ATP).
All organisms are capable of maintaining a relatively stable internal environment. This is accomplished by feedback mechanisms
Living organisms adapt to their environments.
Living organisms have regulatory mechanisms that function in the coordination of the organism’s functions.
is based on structural levels with each level building on the levels below it.
Note that with each step upward in the hierarchy that there are new properties that are not present at the previous level (emergent properties).
Emergent properties are due to the arrangement and interactions of parts as complexity increases
(Reece et al., 2011).
Please note that different textbooks may organize these a bit differently.
are those that are unique to a higher level of organization (this is also consistent with some non-living objects).
1. Reductionism is the study of components of complex “systems”. It makes experimentation easier to look at individual parts instead of the whole system.
2. Systems biology models whole systems by focusing on the interactions of the parts.
between organisms and the physical environment
Elephant and other animals eat leaves and fruit of tree, leaves of tree convert sunlight energy to energy in glucose (photosynthesis), nutrients are cycled etc.
are necessary for all living organisms (also a property of living organisms).
Correlation of structure and function
The cheetah has long legs, large lung capacity and other structures allow it to attain great speed.
The cell is the basic unit of life and all cells have a membrane and DNA
(deoxyribonucleic acid) is passed from parent cells to daughter cells and from parents to their
that lead to regulation of cellular and multicellular activities
The core theme of biology is Evolution.
Theories are much broader in scope than hypotheses. Thus theories are comprehensive and are supported by an accumulation of extensive and varied evidence.
Throughout history humans have attempted to categorize the different species into different groups.
Linneaus suggested two kingdoms based on the ability of the organisms to move: Plants that did not move and Animals that did.
Ernst Haeckel suggested creating a third kingdom Protista
More recently, biologists have attempted to categorize organisms according to the phylogenetic (actual, historic) relationships among them. In 1969, Whittaker proposed the five Kingdom system (Monera, Protista, Fungi, Plantae, and Animalia).
There are currently three domains (Bacteria, Archaea, and Eukarya) The Domain Eukarya is then divided into multiple kingdoms (four or more).
Scientific discoveries are basically made by using one of two methodologies.
Involves observing and documenting phenomena without experimentation. A recent example is the sequencing of the human genome. Conclusions are often based on inductive reasoning. Inductive reasoning uses specific observations to construct general scientific principles.
Hypotheses are simply educated guesses. Null hypotheses are those that suggest that there are no differences between the control and the experimental groups whereas alternative hypotheses are those that suggest a difference.
Deductive reasoning is the opposite of inductive reasoning; from general premises, one extrapolates to the specific results that are expected if the premises are true. In general the predictions are the potential outcomes of the experiments that should be expected if a hypothesis is correct.
the study of interactions between organisms and their environments
includes various sub disciplines of biology (e.g., physiology) dealing with the organism and its natural history.
Population (a group consisting of individuals of the same species living in a given area) ecology deals with the factors that affect the population (specifically its size and changes over time)
Community (the different populations of the different species living in a given area) ecology is related to the interactions of the different species that make up the community
Ecosystem (the biotic and abiotic factors in a given area) ecology is the study of the living organisms and the biogeochemical cycles and energy flow that affect them.
Landscape ecology involves the different types of patches (e.g., corridor of trees lining a river flowing through a sparsely vegetated plain) and research focuses on the factors controlling the exchanges of energy, materials, and organisms among the ecosystem patches.
Global ecology is the study of the biosphere. Global studies are difficult in that there is no control. For example it is difficult to study the specific causes and their exact impacts on Global Climate Change. However, evidence does suggest and most scientists agree that the climate is currently changing and that human activities play a role in that change.
Abiotic factors and climate (the long term prevailing weather conditions of a given area).
Factors that impact climate (moisture and temperature in particular):
Sunlight intensity varies with latitude; the most direct sunlight occurs at the equator.
Season also affects the sunlight intensity (the planet changes position)
Air circulation affects precipitation
Streams and Rivers
Marine Benthic Zones
Note that pollution is a big problem for most of these, that wetlands are often the sites of human development, and that overharvesting resources is decreasing the population sizes of many aquatic species.
Dispersal is the movement of organisms away from areas of high population density or the area of origin. The ranges (areas where the species occurs) are expanded by dispersal. Some species disperse more easily than others.
A few species have wide distributions (e.g., humans) but most of the species of living organisms occur in relatively limited geographic ranges. Biogeography is the study of the distributions of species.
Dispersal or inability to disperse to an area:
Other factors include:
Behavior e.g., habitat selection
Biotic e.g., interspecific competition,
Abiotic e.g., temperature
Unfortunately humans have facilitated some dispersions that have had negative even catastrophic effects
the study of populations (groups of individuals of the same species living in a given area) and their relationships with their abiotic and biotic environments
Population density is the number of individuals that live in a defined area or volume
Changes in population density and number are affected by:
1. Birth rate and death rate
2. Immigration and Emigration
Equation dN/dt = riN
where: d = the change in, N = the number of individuals in a population, t = time, and ri = rmax= the intrinsic rate of natural increase.
Species that experience periods of exponential growth are called r-selected species. They tend to:
1. Reproduce at a young age
2. Produce many small young
3. Offer little parental care
takes into account the factors that regulate population growth and the concept of a carrying capacity (K) or the population size at which stabilization occurs
dN/dt = riN(K-N/K),
where K = carrying capacity, see above for other variables
Species that show a stabilization of N are called K-selected. They tend to:
1. Reproduce later in life
2. Produce fewer, larger, and more developed offspring.
3. Provide a great deal of parental care
Those related to the number of individuals present in the population.
Have their effects regardless of N.
the study of factors that determine the size and structure of populations through time. It involves:
Age structure is important because fecundity (the number of offspring produced in a given time interval) and mortality rates vary for different age groups or classes.
Sex ratio is important in that the number of births is usually more closely related to the number of females rather than the number of males.
summarizes the probability that an individual will survive and reproduce in any given year over the course of its lifetime.
1. determined exactly by counting but the organisms need to be sessile (e.g., plants, barnacles) but this method does not work so well for mobile animals
2. estimated by sampling multiple smaller plots, obtaining an average, and then extrapolating the data
3. The mark-recapture method is commonly used and involves the capturing individuals, then marking them and releasing them. Afterward a second sample is taken and the percent of marked individuals recaptured is recorded. To estimate the total population from these data, researchers make the assumption that the percent of marked and recaptured individuals is equal to the percent of marked individuals in the entire populations.
Equation m2/n2 = n1/N
m2 = number of marked individuals in the second sample
n2 = marked + unmarked in second sample
n1 = number of individuals caught in the first sampling attempt
N = total population size (solve for N)
clumped or with individuals aggregated in patches
uniform or evenly spaced
random or where the position of one individual is independent of other individuals).
Growth rate formula: Growth Rate = (Crude birth rate - crude death rate). Crude birth rate is the number of births/1,000 people & crude death rate is the number of deaths/1,000 people. Depends on: age at which people get married, amount of education, career vs. stay at home women, contraceptive use, number of children desired by the couple, cultural values, and religious beliefs.
The doubling time or the time it takes for a population to double is calculated as follows: Doubling time = 70/Growth Rate (%). Developed countries in general have longer doubling times than developing and third world nations.
Total Fertility Rate (TFR) is the number of children that women are expected to have in their lifetimes.
A country reaches zero population growth when birth rates = death rates and immigration = emigration.
After a country reaches replacement level fertility, population growth can still occur. In fact worldwide the population will still continue to grow even if all nations reach replacement level fertility.
The age structure of a population also affects population growth.
Although most living organisms cannot change their carrying capacities, humans have been able to increase theirs. There are many disagreements concerning the Earth’s carrying capacity for humans. Some people believe that we have already surpassed K, while others think that it may be as high as 1,000 billion.
Decreased infant mortality as a result of increased food supplies, the Agricultural Revolution, the Industrial Revolution, the technology, medicines, and sanitary living conditions.
Increased life spans
Some say yes
Others say no
It makes since that the more people we have, the more impact on resources and the environment. However, the people of developed nations tend to have a larger-
The Ecological Footprint takes into account resources needed and wastes produced by humans. http://www.myfootprint.org/ .
Mandatory limits on number of children
Educational programs extolling the benefits of smaller families
But all of these are controversial
Another possibility is raising the standard of living in third world countries through demographic transition