2D Regulation and Behaviour in organisms Flashcards
Explore how living organisms regulate their internal environment and respond to stimuli.
What are abiotic environmental stresses?
Nonliving factors like floods, droughts, heat, and cold that can affect plants.
Abiotic stresses can significantly impact plant growth and productivity by affecting physiological processes such as photosynthesis and water uptake.
How do plants respond to drought?
By closing their stomata to reduce water loss through transpiration, akin to “plant sweating”.
Stomata are tiny pores on leaves that regulate gas exchange and water loss. Closing stomata during drought helps plants conserve water but also limits gas exchange, which can impact photosynthesis.
What happens to plant leaves during drought conditions?
Some plants roll their leaves into tube-like shapes to reduce surface area, minimizing exposure to dry air and wind.
How do plants respond to flooding?
Flooding deprives plant roots of oxygen.
By producing ethylene, which triggers the formation of air tubes in roots to access oxygen.
Ethylene is a plant hormone involved in various physiological processes, including growth and stress responses like flooding.
Why are heat-shock proteins important for plants?
They help plants survive high temperatures by preventing the denaturation of essential enzymes needed for biochemical reactions.
How do plants protect themselves from cold?
They increase the proportion of unsaturated fatty acids in their membranes to maintain membrane fluidity and prevent freezing.
What role do stomata play in plant response to environmental stresses?
They close during drought to conserve water and open to facilitate cooling and gas exchange under normal conditions.
Stomata are pores on leaves that regulate gas exchange and water loss.
What is the significance of ethylene production in flooded plants?
Leads to the formation of air tubes in roots, which act like snorkels to supply oxygen, preventing suffocation.
What is homeostasis in the context of cell biology?
Refers to the ability of cells to maintain stable and constant internal conditions despite changes in the external environment.
What is passive transport?
The movement of molecules across the cell membrane without the cell expending energy.
It includes diffusion and facilitated diffusion.
Describe diffusion and its role in passive transport.
It’s the movement of molecules from an area of higher concentration to an area of lower concentration. It helps maintain equilibrium of molecules across the cell membrane.
Describe facilitated diffusion.
Uses transport proteins to help molecules (especially larger or polar ones) move across the cell membrane without energy expenditure by the cell.
How does active transport differ from passive transport?
Active transport requires energy (ATP) to move molecules against their concentration gradient, from low to high concentration.
Give examples of active transport processes.
- Protein pumps.
- Exocytosis (exporting materials out).
- Endocytosis (importing materials in).
Why is internal regulation important for cells?
It ensures optimal conditions for metabolic processes, waste removal, and protein synthesis, critical for cell function and organismal survival.
How does metabolism relate to internal cellular environments?
It depends on specific internal conditions for efficient energy production and maintenance of body temperature.
What is the role of cells in maintaining homeostasis?
Cells regulate their internal environments through molecular transport mechanisms to ensure stability, allowing them to perform essential functions necessary for growth, reproduction, and overall organismal survival.
What does the term “endotherm” mean in biology?
These are animals that maintain their body temperature internally, primarily through metabolic processes.
e.g. a human
How does negative feedback function? Provide an example.
- It maintains a target level.
- Example - regulating body temperature through sweating and shivering.
What is positive feedback? Provide an example.
- Amplifies changes away from a target level.
- Example - The ripening of fruits through the production of ethylene gas.
Positive feedback amplifies changes to accelerate processes like childbirth (contractions) ensuring rapid completion of essential biological events.
What role does the hypothalamus play in homeostasis?
Monitors internal conditions like temperature and triggers responses to maintain homeostasis, such as sweating or shivering.
How do endotherms and ectotherms differ in temperature regulation?
- Endotherms regulate body temperature internally through metabolism.
- Ectotherms rely on external sources like sunlight or warmth from their environment.
What role does thyroxine play in thermoregulation?
It increases metabolic rate to generate internal heat, aiding in temperature regulation when the body is cold.
Thyroxine is a hormone from the thyroid gland.
