Plant science Flashcards
Study tropism, respiration, transfusion and other plant systems
What does plant tropism refer to?
The directed movement of an organism in response to external stimuli like gravity or water.
Why have plants developed tropism responses?
Plants need water and light for photosynthesis, so have developed tropisms to ensure they grow towards these sources.
What is positive tropism?
When a plant grows towards a stimulus.
What is the term when a plant (the stem) grows towards light?
Positive phototropism
What is the term when roots grow in the direction of the force of gravity?
Positive geotropism/gravitropism
What is the term when a plants growth is determined by a stimulus of water?
Hydrotropism
Sunflowers are able to follow the movement of the sun throughout the day. What term refers to this?
Heliotropism
What is the term for a plant responding to touch?
Thigmotropism
eg. venus fly trap
Define transpiration
The process of water movement through a plant, and its evaporation from aerial parts (leaves, stems, flowers)
What are the two main functions of transpiration?
It cools the plant, and pumps water and minerals to the leaves for photosynthesis.
What is the overall process of evapotranspiration?
The uptake of water and minerals through the roots (root hair cells), transpiration of water through plant tissue (xylem and phloem), and the release of vapour by leaves (through open stomata)
What is the process of respiration in plants?
Oxygen and glucose react to release water and carbon dioxide.
(Plants get energy through the process of respiration by breaking down glucose)
What’s the process of photosynthesis?
Carbon dioxide and water react to release glucose and oxygen.
(Photosynthesis is a chemical process in which green plants make their own food using energy from the sun. They use this food to grow)
What’s the relationship between photosynthesis and respiration?
They are complementary processes. The glucose produced by photosynthesis is used as a source of energy during respiration. The CO2 produced during respiration is used as a source of carbon for photosynthesis.
What is osmosis?
The movement of water molecules from a solution with a high concentration of water molecules to a solution with a lower concentration of water molecules, through a cell’s partially permeable membrane
Why is osmosis important to plants?
Osmosis helps in the absorption of water molecules from the soil by the root hairs ie allows the plant to drink.
Osmosis maintains the turgidity of plants so they don’t wilt.
What is etiolation?
A process that occurs due to complete or partial lack of light eg leaf litter or shade. Plants grow long, weak, pale stems and smaller leaves as a last attempt to reach a light source.
What is diffusion.
The movement of particles from a region of high concentration to a region of lower concentration, until particles are evenly spread.
Why is diffusion important in plants?
It’s a vital process in plants as diffusion of gasses (CO2 and O2) is required for photosynthesis.
During transpiration, H2O an O2 diffuse from leaves into the environment.
