Biology Unit Test T2 P1 Flashcards
(30 cards)
What property of water allows it to transport nutrients in plants?
Cohesion is the property that allows water molecules to stick to each other due to hydrogen bonding. This cohesive force helps water form a continuous column within the xylem vessels of plants. As water evaporates from the leaves (transpiration), it pulls more water upward through the xylem. This continuous flow is essential for transporting nutrients and maintaining plant structure.
Which bond is primarily responsible for the cohesion between water molecules?
Hydrogen bonds form between the slightly positive hydrogen atom of one water molecule and the slightly negative oxygen atom of another. These weak but numerous bonds hold water molecules together. This gives water its cohesive properties, allowing it to flow in continuous streams. Cohesion is especially important in processes like water transport in plants.
What is the bond angle in a water molecule?
The bond angle in a water molecule is about 104.5 degrees, often rounded to 105 degrees. This angle is due to the tetrahedral arrangement of electron pairs around the oxygen atom. Two of these pairs are bonding pairs with hydrogen atoms, and two are lone pairs. The lone pairs repel more strongly, pushing the hydrogen atoms closer together and creating the bent shape.
What is the high specific heat capacity of water due to?
Hydrogen bonds between water molecules require a large amount of energy to break. This makes water resistant to rapid temperature changes. As a result, water has a high specific heat capacity, meaning it can absorb or release a lot of heat with only a small change in temperature. This property helps stabilize temperatures in organisms and environments.
Why is water considered a polar molecule?
Water is a polar molecule because the electrons are shared unequally between the oxygen and hydrogen atoms. Oxygen is more electronegative, so it pulls the shared electrons closer to itself. This creates a slight negative charge near the oxygen atom and a slight positive charge near the hydrogen atoms. The polarity of water is key to its ability to form hydrogen bonds and dissolve many substances.
What allows ice to float on water?
Ice is less dense than liquid water because of its unique crystalline structure. In ice, hydrogen bonds hold water molecules in a fixed, open arrangement, creating more space between them. This structure causes ice to occupy more volume than the same amount of liquid water. As a result, ice floats on water, which is important for insulating aquatic life in cold environments.
What is the role of water in metabolic processes
Water’s polarity makes it an excellent solvent, as it can surround and separate charged or polar molecules. This allows many biological substances, such as salts and sugars, to dissolve easily in water. Once dissolved, these molecules can move freely, making it easier for chemical reactions to occur. This property is essential for supporting life and cellular processes.
Which property of water is responsible for its high surface tension
Surface tension is caused by the cohesive forces between water molecules at the surface. These molecules are pulled inward by hydrogen bonds with neighboring molecules, since they have no molecules above them to bond with. This creates a “skin-like” surface that resists external force. Surface tension allows small objects, like insects, to rest on water without sinking.
What does the water’s ability to dissolve many substances make it?
Water is known as the universal solvent because it can dissolve a wide variety of substances, especially polar and ionic compounds. This ability is due to its polarity, which allows water molecules to surround and separate solute particles. In biological systems, this property is essential for transporting nutrients, removing waste, and facilitating chemical reactions. Without water’s solvent capabilities, many life-sustaining processes could not occur.
How is water drawn up the xylem of plants?
Capillary action occurs when adhesion and cohesion work together to move water up narrow spaces against gravity. Adhesion causes water molecules to stick to the walls of the xylem vessels, while cohesion keeps the water molecules bonded together. This combined effect allows water to rise through the tiny tubes in plants. Capillary action is essential for transporting water from roots to leaves.
What contributes to water’s ability to act as a solvent?
Water molecules have polar covalent bonds, where electrons are shared unequally between oxygen and hydrogen atoms. This creates an uneven charge distribution, with a slight negative charge near the oxygen and a slight positive charge near the hydrogens. This polarity enables water to surround and separate polar or charged substances, effectively dissolving them. As a result, water plays a vital role in transporting and reacting with various molecules in living organisms.
Which property of water enables aquatic organisms to survive through winter?
When water freezes, it expands and its molecules arrange into a crystalline structure that is less dense than liquid water. This causes ice to float on the surface of lakes and ponds. The floating ice acts as an insulating layer, keeping the water below warmer. This insulation helps aquatic life survive during cold winter months.
What do hydrogen bonds in water allow it to do?
Hydrogen bonds between water molecules require a significant amount of energy to break. Because of this, water has a high heat capacity, meaning it can absorb or release large amounts of heat without changing temperature quickly. This property helps stabilize temperatures in organisms and environments. It is essential for maintaining stable conditions necessary for life.
What is NOT a consequence of hydrogen bonding in water?
Pure water has low electrical conductivity because it contains very few free ions to carry an electric current. The hydrogen bonds between water molecules do not directly affect its ability to conduct electricity. Instead, conductivity depends mainly on the presence of dissolved ions. Therefore, pure water is a poor conductor compared to solutions containing salts or acids.
Which term describes the movement of water against gravity in narrow spaces?
Capillary action describes the movement of water against gravity through narrow spaces. It happens because adhesion causes water molecules to stick to the surfaces of the narrow tubes, while cohesion keeps the water molecules bonded together. These combined forces allow water to rise up through small openings. This process is vital for transporting water in plants.
What is the term referred to when water can act as both an acid and a base?
Amphoterism is the ability of a substance to act as both an acid and a base. Water is amphoteric because it can donate protons, behaving as an acid, or accept protons, behaving as a base. This allows water to participate in a variety of chemical reactions. Its amphoteric nature is important in maintaining the balance of acids and bases in biological systems.
What does the water’s high specific heat capacity help it do?
Water’s high specific heat capacity means it can absorb or release large amounts of heat with only a small change in temperature. This property helps keep temperatures stable in both biological systems and the environment. It protects organisms from rapid temperature fluctuations. Maintaining stable temperatures is essential for proper cellular function and survival.
How does the wate’s high heat of vaporisation benefit organisms?
Water has a high heat of vaporization, meaning it requires a lot of energy to change from liquid to gas. When sweat evaporates from the skin, it absorbs this energy as heat. This process removes heat from the body, helping to cool it down. Evaporation of sweat is an important way the body regulates its temperature.
The fact that water molecules stick to other surfaces is called what?
Adhesion is the attraction between water molecules and other substances or surfaces. This property allows water to stick to things like plant cell walls or glass. Adhesion helps water move upward through narrow tubes, such as in plant xylem. It plays a key role in processes like capillary action.
What terms describe how water can move from the roots to the leaves of a plant?
Water moves up plant stems through capillary action in the xylem vessels. Transpiration, the evaporation of water from the leaves, creates a pulling force called transpiration pull. This force helps draw water upward from the roots through the xylem. Together, capillary action and transpiration enable efficient water transport throughout the plant.
What term describes the force by which water molecules stick to other substances?
Adhesion
What term is the amount of heat required to raise the temperature of 1kg of a substance by 1 degree celsius?
Specific Heat Capacity
What term has a weak bond between two molecules resulting from an electrostatic attraction?
Hydrogen Bond
What term has the ability of a substance to act as both an acid and a base?
Amphoteric substance
