Category1
______is the movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane.
Osmosis
_____is the movement of particles from an area of higher concentration to an area of lower concentration.
Diffusion
_____is the movement of substances against a concentration gradient, using energy from respiration.
Active Transport
____transports water and minerals from the roots to the leaves.
Xylem
_____is the transport of sugars (mainly sucrose) and amino acids through the phloem from sources (leaves) to sinks (roots, growing parts).
Phloem
Active transport requires _____ because molecules are moved against their concentration gradient.
ATP or Energy
____provide energy for sieve tube elements by actively transporting sugars.
Companion cells
Xylem vessels are adapted by having:
(p.s: 2 answers)
Diffusion rate increases with _____ because molecules move faster with more kinetic energy.
temperature
What is a type of membrane that allows some substances to pass through and some not called?
Partially permeable
Alveoli are adapted for diffusion by having: (3 answers)
____ use ____ to absorb minerals from soil, even when their concentration is higher inside the root than in the soil.
Root hair cells (use) active transport
How do the cells in phloem form a tube?
Phloem forms a tube through sieve tube elements arranged end to end, with sieve plates allowing solute movement. These cells lack a nucleus and rely on companion cells, which provide energy for transport
A red blood cell is placed in pure water. Describe what happens to the cell and explain why.
Water enters the red blood cell by osmosis because the cell has a lower water potential than pure water. This causes the cell to swell and eventually burst (lysis) since animal cells lack a cell wall to prevent overexpansion.
If a plant’s xylem vessels are blocked, what will happen to the plant? Explain why.
The plant will wilt and eventually die because water and minerals cannot be transported from the roots to the leaves. Without water, photosynthesis slows down, and the plant loses turgor pressure, leading to wilting.
A scientist injects a radioactive carbon isotope into a leaf. Over time, radioactivity is detected in the roots. What does this experiment show about phloem transport?
This experiment demonstrates translocation, as the radioactive carbon (likely in the form of glucose or sucrose) moves from the leaf (source) to the roots (sink) through the phloem. The presence of radioactivity in the roots confirms that phloem transport is bidirectional, moving substances where they are needed.
A student soaks two identical plant tissues in different solutions—one in distilled water and the other in a concentrated salt solution. Predict and explain the changes in their mass.
Compare the rates of diffusion in a unicellular organism and a multicellular organism, explaining the differences.
Unicellular organisms rely on diffusion because of their large surface area to volume ratio, while multicellular organisms need specialized transport systems due to their small surface area to volume ratio.
Compare and contrast diffusion and active transport, giving an example of each process in living organisms.
Some plants in dry environments have narrow xylem vessels compared to plants in wetter climates. Explain the advantage of this adaptation.
Narrow xylem vessels reduce the risk of air bubbles (cavitation) forming, which could block water transport. This adaptation helps maintain a continuous water column, ensuring efficient transport and reducing water loss in dry environments.
Why is lignin necessary, give 3 reasons
Strength and Support – Lignin provides rigidity to the cell walls of xylem vessels, allowing plants to stand upright and support their structure, especially in tall plants.
Waterproofing – Lignin makes xylem vessels waterproof, preventing water from leaking out and ensuring the efficient transport of water from roots to leaves.
Prevention of Collapse – The strong, lignified walls prevent xylem vessels from collapsing under the tension created by transpiration pull. This maintains a continuous water column for transport.
Some plants can survive without functional xylem for a short time, but they die quickly if phloem transport stops. Explain why phloem transport is essential for survival.
Phloem transports sugars and nutrients produced in photosynthesis to all parts of the plant, including growing tissues, storage organs, and roots. Without phloem transport, energy supply is cut off, leading to starvation and death. Unlike water transport in xylem, which can sometimes occur via diffusion, sugar transport is an active process that cannot happen without the phloem.
Farmers sometimes use high concentrations of fertilizers in soil. Explain how this might affect water movement in plant roots and the possible consequences for the plant.
High fertilizer concentration lowers the water potential in the soil. Instead of water moving into the roots, it may move out of the root cells by osmosis. This can lead to wilting, reduced growth, and, in extreme cases, plant death due to dehydration.
A student investigates diffusion using agar jelly containing phenolphthalein and sodium hydroxide. When placed in hydrochloric acid, the color disappears. How could the student modify the experiment to study how surface area affects diffusion rate?
Some marine fish actively transport excess salt out of their bodies using specialized cells in their gills. Explain why active transport is necessary for this process and discuss the energy implications for the fish.
Active transport is necessary because the concentration of salt in the fish’s body is lower than in seawater, meaning salt must be moved against the concentration gradient. This process requires energy (ATP) from respiration. Since marine fish constantly lose water by osmosis, they must balance salt levels by actively excreting excess salts. This energy demand means they need a high metabolic rate and an efficient oxygen supply to sustain ATP production.