Mid-Term 1 Prep Flashcards
What are the 7 characteristics that we can use to define life?
GO ERRRA!!!
Order/Organized (usually into cells)
Ability to process energy/metabolize
Growth and Development (increase in complexity)
Ability to reproduce
Response to environmental stimuli
Regulation – homeostasis
Adaptation (long-term)
What is the order of biological organization (from molecules to the biosphere)?
Chemical:
Molecule
Cellular:
Organelle
Cell
Tissue
Organ
Organ System
Ecological
Organism
Population
Community
Ecosystem
Biosphere
What is the first level of organization where the properties of life emerge?
The level of the cell.
What happens to elements in the ecosystem? (cycle)
Matter is continuously recycled in ecosystems.
Producers (plants) create food, consumers eat food and produce waste, which returns some nutrients back to the environment. The rest are stored in the animal until the it dies, then decomposers release the nutrients back to the soil. Plants also decompose eventually.
What happens to energy in the ecosystem? (cycle)
It enters as sunlight and exits eventually has heat.
Sunlight energy, converted by plants to chemical energy, converted to kinetic energy by animals, eventually much is converted to heat through various metabolic processes.
What evidence do we have that shows that all life is unified?
The unity of life is based on DNA. There are fundamental similarities among very different kinds of living things.
All organisms use the exact same code (ATCG) to form DNA, the diversity of life arises from differences in DNA sequences.
Bacteria and humans are different because they have different genes, but the instructions on how to “make them” are written in the same language and use the same molecular building blocks.
What do we mean when we talk about the diversity of life?
There are tons of species that we can group according to similarities and relationships (Bacteria, Archaea, Eukarya). The diversity of life arises from differences in DNA sequences.
How does the theory of evolution describe both the unity and diversity of life?
There are fundamental similarities among very different kinds of living things. Such basic similarities imply relatedness, therefore a “common ancestry”.
Unity = Descent from a common ancestor.
Diversity = species diverged from their ancestors over time.
What is a hypothesis?
A testable explanation for a set of observations based on available data. A logical prediction. IF…THEN
What do we mean by a controlled experiment?
A large number of samples/individuals.
Control groups give you something to compare the experimental groups to.
The experimental group has only one thing (variable) different than the control group.
Randomized (to control for potentially interfering variables) and blinded (to avoid bias)
Was mimicry helpful to non-poisonous King snakes in an environment where there were no poisonous coral snakes?
No. Mimicry made the king snakes more visible which was only helpful when predators knew to avoid those colour due to the poisonous coral snakes.
What is an atom?
An atom is the smallest unit of matter which still displays the characteristic properties of an element. Made of protons, neutrons and electrons.
What is an element?
An element is a substance that cannot be broken down to other substances by ordinary chemical means. All matter is made of elements.
What is a molecule?
Molecules are formed when 2 or more atoms (of the same element) combine together.
What is a compound?
A compound is a substance consisting of two or more elements combined in a fixed ratio. Compounds can have very different properties than its individual components.
Only _______(#) elements make up 96% of what is inside of life. What are they?
Four. Oxygen, Carbon, Hydrogen and Nitrogen. (from biggest to smallest)
What elements make up 98% of all living matter?
Oxygen, Carbon, Hydrogen, Nitrogen, Phosphorus, and Sulfur! (from biggest to smallest)
CHNOPS!!
What goes into carbohydrates and proteins? (Related to: What elements make up 96% of what is inside of life?)
Carbohydrates = CHO (Carbon, Hydrogen, Oxygen)
Proteins = primarily CHNO…and a bit
of S. (Carbon, Hydrogen, Nitrogen, and Oxygen… and Sulfur)
What are the 3 subatomic particles?
Protons, neutrons and electrons.
What are the charges of the 3 subatomic particles?
Protons are positive.
Neutrons are neutral.
Electrons are negative.
What are the sizes of the 3 subatomic particles? Where are they located within the atom?
Protons and neutrons are bigger, approximately the same size, and occupy the nucleus.
Electrons are teeny tiny and occupy “orbitals” or “energy shells” around the nucleus.
Atoms are mostly empty space!
Which subatomic particle is responsible for defining the element?
Protons. All atoms of a particular element have the same number of
protons.
Which subatomic particle is responsible for an element’s reactivity?
The atom’s reactive properties are based on the electrons.
What is the atomic number?
The number of protons specific to an element.
For example, carbon has 6 and oxygen has 8.
What is the atomic mass?
The mass of a single isotope or single atom. The sum of an atom’s neutrons and protons.
i.e. Carbon, with its six protons and six neutrons has an atomic mass of 12
What is the atomic weight?
The average weight of an element with respect to all its isotopes and their relative abundances.
What is an isotope? Do these behave differently?
An atom with more or less neutrons than normal (normally protons = neutrons). The atom behaves the same as normal but has a different atomic mass. Some may be radioactive.
How many electrons fit into a single orbital? How are orbitals related to energy?
Only two electrons can occupy an orbital at any one time. Atoms with more than two electrons have a series of orbitals at increasing distances from the nucleus. The further an electron is from the nucleus, the greater its energy
How many electrons and orbitals fit into the first shell and second shell?
The first shell contains 1 orbital and can hold 2 electrons. The second shell contains 4 orbitals and can hold 8 electrons.
What do we call electrons in the outer shell that dictate how the atom reacts?
The outer shell is the valence shell, and the electrons in it are valence electrons. They determine the chemical properties of the atom and are available for chemical bonding.
What is a stable number of electrons in a valence shell?
Most stable when full. Most of the elements important in biology need eight electrons in their outermost shell.
What are the three basic types of chemical bonds?
Covalent Bonds can be nonpolar (equal sharing) or polar (unequal sharing).
Ionic Bonds (one donates, one receives, creating ions)
Hydrogen Bonds
What is a double (or triple) bond?
Formed when atoms share two (or three) pairs of electrons. Prevents rotation unlike single bonds.
i.e. O2 has a double bond.
What is electronegativity? How does it affect bonds?
The ability to attract electrons from other atoms in a molecule. The closer the outer shell is to being full the more electronegative the atom. If a bond forms between two atoms with different electronegativities the bond will be “polarized”.
Do electrons closer to or further from the nucleus have a higher energy level?
The further an electron is from the nucleus, the greater its energy.
What are polar bonds and why is this important for water (H2O)?
Polar covalent bonds include the unequal sharing of an electron.
In H2O the oxygen holds the electrons closer giving it a slight negative change and the hydrogen a slight positive change. This allows water to hydrogen bond!
What is a hydrogen bond? What compound is this most relevant to?
A weak electrical attraction between polar molecules. A slightly positive hydrogen of one molecule attracts a slightly negative atom from another molecule. Usually shown as a dotted line.
Water’s two hydrogen atoms form a “V” shape. H2O will hydrogen bond to other H2Os.
What are some of the unique properties of water because of hydrogen bonding? (7 properties)
Freezing point (O°C) and boiling point (100°C) are higher than expected so it’s usually liquid (good for chem reactions).
Universal solvent.
The most abundant liquid.
High heat of vaporization (water absorbs lots of heat to evaporate, evaporative cooling) and high heat capacity/specific heat (changes temp. slow, buffer).
Strong cohesion/adhesion(plants! and water tension/meniscus).
Ice floats, it’s less dense than the liquid water due to its lattice structure (lake life).
What is a solution?
A liquid that is a mixture of 2 or more substances.
What is a solvent? What’s a common solvent?
The dissolving agent in a solution – usually a liquid. Water is the most versatile solvent known because of its polarity.
What is a solute?
A substance that is dissolved in a solution (often a solid).
What is the hydrogen ion concentration and pH of pure water?
In one litre of pure water the H+ concentration is 1x10-7 moles and the pH is 7 (neutral).
How does the pH (the potential of Hydrogen) scale work?
pH describes how acidic or basic a solution is on a scale of 0 to 14. It is the negative log10 of the hydrogen ion concentration.
Acids = 0 to 7, add H+ to solutions.
Neutral = 7, equal H+ and OH-
Bases = 7 to 14, add OH- to solutions (a.k.a. subtracting H+).
How does the pH scale increase/decrease?
It’s a logarithmic scale, so every change in pH of 1 unit represents a 10-fold change in the [H+] of a solution.
pH 6 = 10 x more H+ than 7
pH 5 = 10 x 10 = 100 times more H+ than 7
What is a buffer? Why is it important?
Buffers are solutions that resist changes in pH when an acid or a base are added to them.
The molecules and chemistry of life function within very narrow ranges of pH.
What is the bicarbonate buffer system?
A buffering system in mammalian blood (and seawater). This system is in equilibrium and is reversible. When you add CO2 (by breathing) you shift the equation to the right and get more H+, and vice versa.
What causes acid rain? What is it’s pH?
Mostly burning fossil fuels (sometimes volcanoes, metal smelting) = sulphurous and nitrous oxides = sulphuric and nitric acids = acid rain, snow, fog, hail, or even dust. Regular rain = pH 5.6, acid rain = pH 4.2 to 4.4
What are some of the effects of acid rain?
Additional acid alters the pH of environments. Run off adds toxic elements into aquatic systems. Dissolves shells. Leaches toxins from soil, robs nutrients, makes plants weak. Damages roots, leaves and bacteria.
What causes ocean acidification?
The increase in CO2 from fossil fuel burning over the past 150 years. Carbon dioxide dissolves into water and becomes carbonic acid (H2CO3) which adds more H+ to the water.
What happens to the pH of the oceans as they become more acidic (or less basic)? What’s the approx. ocean pH?
The pH becomes lower. Prior to industrialization, oceans were slightly alkaline with a pH of 8.2, today it is about 8.1 (which is significant, pH is logarithmic).
How does ocean acidification affect sea creatures?
A lower pH dissolves calcium carbonate shells and exoskeletons.
Coral reefs require carbonate ions for their skeletons. Coral reef ecosystems are safe havens. Many shelled organism are important to food webs.
Why is carbon the backbone of so many biologically relevant molecules (4 reasons)?
It’s abundant; it can form four covalent bonds; can easily form and break bonds with oxygen and other carbons (important for respiration/ photosynthesis, carbon chains are useful). Carbon is super versatile (length, double bonds, branching, rings).
How many valence electrons does carbon have? How many bonds does it want?
Carbon has four electrons in the outer valence shell, and can form four covalent bonds.
What is the basic formula for a hydrocarbon?
Contains only hydrogen and carbon. Carbon forms the skeleton or backbone.
What is the basic formula for a carbohydrate? Hydrophobic/philic?What are they used for?
Hydrated Carbon – they all contain C and H2O. Contains hydroxyl groups (OH) & carbonyl groups (C=O).
Tend to be hydrophilic due to many OH groups. Used for energy storage (sugars/starches).
What is the basic formula for a protein?
Polymers made from various combinations of 20 amino acids. A carbon backbones with a carboxyl (COOH) and amino group (NH2). The carboxyl and amino groups of different molecules are joined to create proteins.
What are nucleic acids?
What is their basic formula?
Are macromolecules including Ribonucleic Acid (RNA) and Deoxyribonucleic Acids (DNA). Made of monomers called nucleotides (made of 5C sugar, a phosphate group PO4, and a nitrogen base).
Dehydration synthesis joins nucleotides: sugar to phosphate.
What are lipids? What are two common properties between lipids?
Includes compounds commonly known as fats, oils, and waxes. Includes fats (triglycerides), phospholipids and steroids. They are not huge macromolecules. Vary a lot in structure and function but are all hydrophobic.
