A1.1 Water Flashcards
State that the first cells originated in water
Cells first originated in water
List reasons why water is a substance on which life depends
The first cells originated in water
Water is the solvent
Water is a metabolite
Water is a temperature buffer
Water maintains biological structures
Describe the structure of an atom.
An atom is composed of a nucleus with protons and neutrons and is surrounded by electron orbits
Outline the formation of ionic and covalent bonds between atoms.
Covalent Bond : Two atoms held together that share one or more pair of electrons
Ionic Bond : Attraction between a positively charged ion (cation) and an negatively charge ion (anion)
Explain the sharing of electrons between atoms in a polar covalent bond.
In a polar covalent bond since one side has more protons it has a stronger pull on the electrons resulting in a slightly negative charge on the side with a bigger pull and a slightly positive charge on the side with a weaker pull
State the location of the polar covalent bond within a water molecule.
Polar Covalent bonds are between the two hydrogen molecules and oxygen molecule
Explain the partial charges of the oxygen and hydrogen atoms within a water molecule.
The hydrogen’s are slightly positive and the oxygen is slightly negative. This is due to oxygen’s nucleus which has a stronger pull
Outline the cause of the formation of hydrogen bonds between water molecules.
Hydrogen bonds are formed because of the attraction between the slightly negative side of hydrogen and the slightly positive side of oxygen. And vice versa
Outline the consequences of the collective strength of hydrogen bonds between water molecules.
Hydrogen bonds are weak individually however collectively contribute to the stability and retainment of water on Earth.
Define cohesion.
Cohesion is the property of water in which it makes hydrogen bonds with itself, causing water molecules to stick together
Describe how water moves through the xylem of a vascular plant.
Transpiration (evaporation) occurs through stomata of a leaf and creates negative pressure
The tension created by transpiration “pulls” water in the plant xylem drawing it upwards
Cohesion pulls up water molecules in a chain from the top-most water molecule
Outline the cause of surface tension.
Surface tension is caused by the cohesion of water molecules on the surface of the water which forms a barrier of hydrogen bonds. These hydrogen bonds are also stronger as there is no water molecule in the air meaning it creates an inward force and stronger bonds with other water molecules on the surface
State a benefit to living things that results from surface tension.
Surface tension allows organisms such as water striders to live on. As they are not strong enough to break the water tension.
Define adhesion.
Adhesion is the property of water in which it bonds with other substances that are polar
Define polar.
Polar means there is an unequal sharing of electrons within atoms
Define ion.
An ion is an atom that has lost or gained an electron and has an unequal number of electrons to protons
Compare cation and anion.
Cation, is an ion that is positive
Anion, is an ion that is negative
Explain why water is attracted to molecules that are polar or charged.
The slightly negative side of a water molecule is attracted to the positive charge of molecules that are polar or charged
The slightly positive side of a water molecule is attracted to the negative side of a polar or charged molecule
Outline the cause of capillary action.
Capillary action is the movement of water through a narrow space, often in opposition to external forces like gravity. Adhesion of water to the walls of the vessel will cause an upward force on the liquid and cohesion will drag the chain of water behind it
Describe capillary action in plant tissue.
Capillary action helps bring water from the roots all the way up to the branches and leaves. Adhesion allows water to stick to the xylem walls which will cause an upward force on the water.
Outline the cause and effect of capillary action in soil.
Capillary action in soil means moving though soil pores on spaces between soil particles the same way it moves through a tube
Identify solvent and solutes of a solution.
Solvent : the liquid in which a solute dissolves
Solutes : the substance that dissolves in a solvent
Define solvation.
Solvation is the interaction of a solvent and a dissolved solute
Explain why water is able to dissolve charged and polar molecules.
Because water is a polar solvent attracted to polar and charged molecules which are solutes.
Outline the solvation of hydrophilic and hydrophobic substances.
Hydrophobic means water fearing, because they aren’t polar or charged they do not dissolve within water
Hydrophilic means water loving, because they are charged or polar they dissolve within water
State an example of the function of a molecule depending on it being hydrophobic and insoluble.
Cholesterol - component of membrane structure
State an example of the function of a molecule depending on it being hydrophilic and soluble.
Salt dissolving in water
Outline the role of water as a medium for metabolism.
Cytosol the liquid part of the cytoplasm, is a structure that contains dissolved salts, fatty acids, sugar, amino acids and proteins such as enzymes. These dissolved substances are needed to carry out the metabolic processes required to keep the cell alive.
Describe the role of water as a medium for transport in vascular plants.
Water is used to transport dissolved ions and sugars through the body of vascular plants.
Describe the role of water as a medium for transport in animal blood.
Water is used to transport molecules through the body within the blood of animals. Blood plasma transports salt ions, amino acids, proteins, glucose and waste products of metabolism.
Define physical property.
A physical property is a measurable characteristic of a matter that exists without the matter reacting or interacting with other things
List physical properties of water that are consequential for animals in aquatic habitats.
Buoyancy
Viscosity
Thermal Conductivity
Specific Heat capacity
Outline the cause and effect of buoyancy.
Cause : The upward force on an object when submerged in water
Effect : If the buoyant force is stronger than the object’s weight, the object will float.
Outline the cause and effect of viscosity.
Cause : due to the amount of friction the molecules experience as they flow over each other
Effect : A thick fluid is more viscous than a thin fluid
Compare viscosity of air to water to blood.
Air has very minimal friction between molecules and is therefore less thick and less viscous than water which has more friction between molecules. However blood has more friction between molecules and is more thick and viscous
Define thermal conductivity.
Thermal conductivity is a measure of a material’s ability to move heat across a temperature gradient.
Compare less conductive to more conductive materials.
Less conductive : Heat slowly moves through material. Better for insulating and conserving heat
More conductive : Heat rapidly moves through the material. Better for absorbing and transferring heat
Outline a consequence to life of the thermal conductivity of air and water.
Marine mammals are exposed to both air and water. The marine mammal will lose more heat within water than within air because water is able to rapidly absorb heat whereas air isn’t. This would mean that within colder regions, marine mammals would need an insulating layer of some sort in order to submerge themselves in water.
Define specific heat capacity.
Specific heat capacity is the amount of energy required to lift the temperature of a chemical per unit mass
Describe why water has a high specific heat capacity.
Water has a high specific heat capacity because of the amount of energy required to collectively break all hydrogen bonds. The amoumt of heat energy absorbed when trying to break thses bonds increases the temperature
State two benefits to life of the high specific heat capacity of water.
The high specific heat capacity allows the water to maintain a consistent temperature, which provides a stable environment and habitat of living things
Outline a benefit to life of water’s high specific heat capacity.
Because living bodies contain a lot of water our body temperature is slow to to change when our environmental temperature changes.
Compare the physical properties of water to those of air.
Water
Greater buoyant force
Greater viscosity
Greater thermal conductivity
Greater specific heat capacity
Air
Lower buoyant force
Lower viscosity
Lower thermal conductivity
Lower specific heat capacity
Describe how the black-throated loon (Gavia arctica) and/or the ringed seal (Pusa hispida) interact with the physical properties of water in their habitat.
The black throated loon is able to float on water without expending too much energy due to the buoyancy of water. However in the air it requires a lot of energy to stay aloft. The water is viscous, so the loon takes advantage of it’s streamline shape to move through the water and in the air can easily move through it when flying. The loon doesn’t lose as much body heat to the air because air has low thermal conductivity. However because the air has a low specific heat, it’s temperature changes rapidly
Buoyancy in water allows the seal to stay afloat without expending a lot of energy. However the water is viscous, so the seal has adaptations to streamline as it swims. Water has a greater thermal conductivity than air, so the seal needs to insulate itself with blubber to maintain body temperature. However, because of the water’s high specific heat capacity, the water maintains a stable water temperature
Explain the hypothesis that asteroids are responsible for the origin of water on Earth.
Asteroids and comets up to a few 100 kilometers away seem like the most likely sources of most of Earth’s water. Studies of rocks that date to soon after the formation of Earth suggest that water may have begun to exist on Earth as early as 4.4 Billion years ago.
State two reasons why water was retained on early Earth
Water was retained because of the gravitational pull and the distance from the sun
Explain why the presence of water is considered fundamental to the search for extraterrestrial life.
Water is essential for all life because it functions as a solvent allowing the key chemical reactions to take place.
Define “Goldilocks zone” in relation to the search for extraterrestrial life.
The goldilocks zone is when a planet is nor too far or too close to the sun so that the water remains liquid.
