Honors Bio Midterm

The following list is an overview of the topics covered on the midterm exam. The exam is made up of approximately 140 multiple choice questions pulled from these topics and several short answer questions. Between 20-30 of these questions will be specifically asking you to analyze data or experimental information (such as tables or graphs) in order to answer questions related to these topics. There will be several short answer questions on the topic of homeostasis and its application throughout the semester. Although many of the topics listed below are vocabulary terms, you should focus your studying on the concepts related to those terms instead of memorizing definitions.

Definition of science -

way of gathering organized evidence, observing, thinking, and “knowing” (Earth is always changing), goal is to provide a natural explanation for natural events - nothing supernatural

Hypothesis -

a scientific explanation for a set of observations that can be tested in ways that support or reject it 

Variables (ind. and dep.) - 

independent variable changes only when done deliberately, dependent variable depends on the independent to change - scientists adjust the independent to observe results from the dependent variable

Theory -

unsupported/unproven ideas, society accepts whichever one is more popular, adapted into beliefs and followed until proven false/true - a well-tested explanation that unifies a broad range of observations and hypotheses and that enables scientists to make accurate predictions about new situations

Scientific methods -

step-by-step way of solving problems of learning about the world

• Ask a question - what do you want to know?

• Do research - find out what’s already known

• Make a hypothesis - guess the answer to your question

• Test the hypothesis - do experiments to see if your guess is right

• Analyze the results - look at what happened and figure out what it means 

• Draw a conclusion - decide if your guess was correct or not

Limitations of science -

limitations that stop us from answering certain questions (ie. What is the meaning of life?) there are also limitations on technology and experiments

Bias -

when a scientist favors an idea/side based on past experiences, connections, or job. A particular preference or point of view that is personal rather than scientific

Characteristics of life -

living things are made up of basic units called cells, are based on a universal genetic code, obtain and use materials and energy, grow and develop, reproduce, respond to the environment (stimuli), maintain a stable environment, and change over time

Homeostasis -

a state of balance in which all needs are met in the ecosystem, an ecosystem will have limiting factors or buffers to balance the ecosystem 

Observations -

an idea recorded based on what is seen/observed, not using numerical measurements

Metabolism -

the combination of chemical reactions through which an organism builds up or breaks down material

Parts of an atom -

made up of a nucleus (protons and neutrons) that is surrounded by moving electrons, atoms charge determines what element it is

Isotopes - 

elements that have the same number of protons but different numbers of neutrons

Ions -

what an atom becomes once it is positively or negatively charged once it loses or gains an electron

Element -

a pure substance that consists of entirely one atom, table of elements has non-metals and metals

Compound -

a substance formed by the chemical combination of two or more elements in definite proportions 

Molecule -

the structure that results when atoms are joined together by covalent bonds, “atom is to element as molecule is to compound” - bigger molecules (macro-molecules)

pH -

a scale that determines the alkalinity and the acidity, number of OH- or H+ ions (hydroxide and hydrogen), the lower on the scale, the more acidic and the higher on the scale the more basic, buffers are required to balance fluctuations in an environment, weak acids or bases to balance out strong acids or bases

Polarity -

when an atom is positively or negatively charged - POLAR water atoms are able to connect slightly positive charged atoms to slightly negative charged atoms and the other way around (why water wants to stick together / stick to things)

Covalent bonds/Ionic bonds -

covalent bonds are when two atoms share electrons and ionic bonds are when an atom gives one or more electrons away or takes one or more electrons

Valence electrons -

electrons that are exchanged/shared through covalent and ionic bonds

Catalysts/enzymes -

catalysts act as a kickstart to chemical reactions, they speed up the reaction, enzymes act as a biological catalysts and speed up processes, enzymes are proteins (shape gives them their job)

Activation energy -

the energy that is required for a chemical reaction to occur

Special Properties of Water -

water forms hydrogen bonds that create large chains, water’s ability to dissolve substances, sticks together and to other objects, requires more heat to move molecules, one of the few compounds in liquid state, LOTS OF BONDS

Basis of organic molecules -

carbon's ability to make single, double, and triple bonds creates macromolecules that are the four basic organic molecules of life

Types of organic molecules -

carbohydrates - (CHO) store energy and form biological membranes, lipids - (CHO) store energy, important part of biological membranes and waterproof coverings, proteins - (CHON) control rate of reactions and regulate cell processes, create cellular structures, fight diseases, and bring substances in and out of cells , nucleic acids - (CHONP) store and transmit hereditary and genetic information

Subunits of the original molecule -

amino acid (protein), nucleotide (nucleic acid), and mono/polysaccharides (carbohydrates).

Chemical reactions -

When two reactants have a reaction that is kick-started by activation energy and is then sped up by catalysts, causes the atoms to rearrange

Levels of ecology -

The levels of ecology starting at the lowest and going to the highest are: an individual organism, a population - a group of individuals that belong to the same species that live in the same area, a community - an assemblage of different populations that live together in a defined area, an ecosystem - is all the organisms that live in a place, together with their physical environment, a biome, and a biosphere.

Trophic level labels -

Producers (Autotrophs), Primary Consumers (Herbivores), Secondary Consumers (Carnivores/Omnivores), Tertiary Consumers (Top Carnivores), Decomposers (Detritivores)

Food chains/webs -

food chains are a series of steps in which organisms transfer energy by eating and being eaten - energy passed through an organism, food webs are complex systems of how organisms are affected in the food chain, i.e when a bull frogs food supply lessens the frog is affected, the consumers and producers are affected

Biomass -

total amount of living tissue in a trophic level: measured in grams of organic matter

Sources of energy for food chains -

A producer's main source of energy is the sun - photosynthesis or chemosynthesis, herbivores (first level consumer) eats the producers, carnivore (second level consumers - fourth level consumers) eat the herbivores

Types of autotrophs -

plants such as trees, grass, bushes, flowers, algae, & bacteria

Ecological pyramids -

pyramids of energy - how energy passes through each trophic level, pyramids of biomass - the amount of biomass on each level, pyramid of numbers - shows the relative number of individual organisms in each level

10% rule -

a rule for pyramids of energy, each layer decreases the energy intake by 10%, the primary producers start at 100% energy (energy gained from the sun) and as the pyramid goes up through consumers, the energy will decrease from 100% to 10% to 0.1% and so on.

Decomposers -

organisms that break down animal remains or plants - transfer matter back into the Earth (later goes back into a plant creating a cycle of matter), examples are vultures and mushrooms/bacteria

Water cycle -

• Steps: precipitation, evaporation, transpiration

• Human Activities: deforestation, irrigation

• Problems: floods and droughts, soil less plantative over time

Carbon cycle - 

• Steps: photosynthesis

• Human Activities: burning fossil fuels, deforestation

• Problems: more greenhouse gases, climate change, extra carbon is released into the atmosphere, ocean acidification, water level rising - ice melting (bc of global warming)

Niche -

describes not only what an organism does, but also how it interacts with abiotic and biotic factors

Nitrogen fixation -

the process of turning nitrogen from the air into forms that plants and animals can use like ammonia or nitrates - anomia can be formed by factories from turning fertilizers 

Sources of nitrogen for plants and animals -

Plants: soil nitrogen or nitrogen fixation, decomposed matter, Animals: get nitrogen by eating plants or other animals, nitrogen is used to make proteins and DNA

Habitat Greenhouse effect - 

The greenhouse effect is the process that traps gases to heat Earth, keeping the planet warm to support life. It plays a crucial role in maintaining habitats but with the global heating, habitats are not homeostatic (due to increased heat)

Energy vs. matter in ecosystems -

energy flows in one direction through an ecosystem - starts with the producers and ends with decomposers, matter cycles through an ecosystem - after an organism dies its matter is decomposed into the land and is brought back into plants that grow from the decomposed soil

Limiting factors -

the factors that kill off a population when an ecosystem’s carrying capacity is surpassed to create balance (homeostasis) because the ecosystem can only hold so many of one species

Weather vs. climate -

weather is the daily conditions while climate is the Earth as a whole on a longer timeline

Predator/prey relationship -

predators can affect the size of prey populations in community and determine the places prey can live and feed

Types of symbiosis -

mutualism: when both organisms benefit from the relationship (Bees and flowers), Commensalism: one organism benefits while the other is unaffected (Whales and barnacles), Parasitism: when one organism benefits but the other is harmed (Human and parasite)

Primary/secondary succession -

primary succession is when an ecosystem grows on sterile land over a long period of time, secondary succession is when an ecosystem changes after a disturbance

Aphotic/photic zone -

photic zone is a sunlit region near the surface where photosynthesis can occur, the aphotic zone is a dark region that is too dark for photosynthesis to occur

Determining terrestrial biomes -

Terrestrial biomes are determined primarily by climate factors such as temperature and precipitation

Benthic zone -

Zone at the bottom of the seafloor. Organisms that live there are called Benthos. Animals that live in/on rocks and sediment

Pop. distribution -

The number of individuals in a given area

Types of aquatic ecosystems -

the two types of aquatic ecosystems are freshwater and saltwater ecosystems - determined by depth, temperature, flow, and the level of dissolved nutrients

Population density -

How individuals are spread out in a unit of an area - randomly, uniformly, or clumped

Geographic range -

the range of which a population inhabits.(Varies depending on species)

Age structure -

the number of males and females of each age in a population, most animals cannot reproduce until a certain age (only females produce offspring)

Birthrate/deathrate -

The rate at which a species is born and the rate at which a species dies. (Both affect age structure and population.)

Logistic growth -

When a population grows in size but later stabilizes in growth. (Also known as S-Curve)

Immigration/emigration -

Immigration is when individuals move their population from somewhere else and emigration is when individuals move out of the population's range

Exponential growth -

under ideal conditions with unlimited resources, a population will grow exponentially; the size of each generation of offspring will be larger than the generation before it

Carrying capacity -

the maximum number of individuals of a particular species that a particular environment can support

Density dep. vs. density ind. limiting factors -

density dependent limiting factors require the population to be at a certain density for it to take place (limiting factors only occur when population gets too high), density independent limiting factors are things that occur no matter a population's density (natural processes: hurricanes, floods, or tornadoes)

Monoculture -

the practice of clearing large areas to plant a single highly productive crop year after year

Demographic transition -

a dramatic change from high birthrates and death rates to low birthrates and death rates. Three Stages to this transition, Stage 1: birthrate and death rate are equally high; Stage 2: death rate begins to fall, but birth rates remain high; Stage 3: birth rate falls to meet death rate. Has occurred in the United States, Japan, and most of Europe

Invasive/introduced species -

species that are introduced accidentally or purposefully into an ecosystem that kill off native species by consuming too much food, competition, or killing off species directly - invasive species grow dramatically in number and will breach the carrying capacity and outhunt many species

Sustainable development -

using resources in an environmentally cautious way to not cause long-term harm - provides for human needs while preserving the ecosystems to produce natural processes (should not cause harm to soil, water, or climate)

Renewable/nonrenewable resources -

renewable resources are sources that are able to replenish themselves at the same rate that it is being used (sunlight), nonrenewable sources are sources that are unable to be replenished with the rate it is being consumed/used

Desertification /Biomagnification -

desertification : the process of farming, overgrazing, seasonal droughts, and climate changes - changes farmland to deserts, biomagnification is the concentration of toxins in an organism as a result of ingesting other plants or animals in which the toxins were more widespread

Acid rain -

made from nitrogen and sulfur combined with water vapor, forms nitric and sulfuric acids. Air born acids fall as acid rain. Lowers pH of soils and aquatic ecosystems

Smog -

gray-brown haze formed by chemical reactions among pollutants (released by industrial processes and automobile exhaust) - ozone is a product of these reactions, in lower atmosphere levels it causes harm to organisms

Biodiversity -

the total of all the genetically based variation in all organisms in the biosphere Three levels: Ecosystem (variety of ecosystems in the biosphere [or a continent/country/state etc.]), Species (number of species in a given area like an ecosystem), Genetic (amount of genetic variation in species, often correlates with the number of individuals in that species)

Threats to biodiversity -

• Habitat Destruction: deforestation, urbanization, and agriculture can destroy or fragment natural habitats, making it difficult for species to survive

• Climate Change: shifts in temperature and weather patterns disrupt ecosystems, threatening species that cannot adapt or migrate

• Pollution: chemicals, plastics, and other pollutants can poison ecosystems, affecting plants, animals, and water quality

• Overexploitation: overhunting, overfishing, and unsustainable resource use deplete populations and ecosystems

• Invasive Species: non-native species can outcompete, prey on, or introduce diseases to native species, leading to ecological imbalances.

Cell theory -

All living things are made up of cells, cells are the basic units of structure and function in living things, new cells are produced from existing cells

Prokaryote/eukaryote -

The prokaryote do not separate the genetic material within a nucleus, the eukaryotic cell’s nucleus separates the genetic material from the rest of the cell

Organelles -

act like specialized organs (literally called “little organs”), a specialized structure that performs important functions in a cell

Plant vs. animal cells -

plant cells have cell walls while animal cells have cell membranes instead, plant cells have chloroplasts which are used for photosynthesis, both have mitochondria which controls the energy in a cell

Cell membrane -

only in animals, acts as a security to the cell, controls which substances can enter and exit the cell - a thin, flexible barrier, surrounds the cell

Levels of biological organization -

molecule → organelle → cell → tissue → organ → organ system → organism → population → community → ecosystem → biome → biosphere

Homeostasis -

when all the physical and mental needs are met - everything is balanced

Examples of Conditions -

being thirsty, hungry, hot, or cold, and your body responding to return by drinking, eating, sweating, or shivering

pH/Buffers -

buffer is a compound that prevents sharp, and sudden changes in your body’s pH

Maintenance at varying levels (organism, cellular) -

single-celled organisms, like the freshwater protozoan, must be able to carry out all of its functions necessary for life.

Application to Ecology -

To maintain homeostasis, unicellular organisms grow to respond to the environment, transform energy, and reproduce.

Enzymes -

protein catalysts that speeds up the rate of specific biological reactions