The Internal Environment of Organisms Flashcards
What is homeostasis?
a condition of balance in your body that happens automatically to create and maintain an environment for your brain to function
Do all living organisms have homeostasis?
Yes, all living organisms have homeostasis. It is a fundamental characteristic of all living systems.
In animals, what helps to maintain homeostasis?
internal organs that are similar in function to those in humans help to maintain homeostasis
In amoebas, how do they remove waste?
the removal of toxic waste happens without complicated internal organs and with few specialized structures
What can losing homeostasis for an extended period of time mean to an organism?
Death
What is needs to maintain homeostasis? Explain both mechanisms
- organism must be able to sense when changes have taken place in the external and internal environment
- it must be able to respond with appropriate adjustments
Explain each step of what happens to the human body when it senses cold
Humans can monitor stimuli, or external signals such as cold, because we have sensory neurons in our skin that allows us to feel the outside temperature. Once the message “cold” is received in the brain, our body can respond by changing blood flow. Our heart rate may increase. Certain blood vessels may constrict. This change is involuntary or automatic.
Are most homeostasis reactions voluntary or involuntary?
Involuntary
What will the human body start to sacrifice to keep the organs balanced?
The body responds to cold temperatures by diverting circulation to keep the most important internal organs warm.
What will the human body do if it senses that it is getting too hot?
The circulatory system diverts blood flow away from the internal organs. This protects them from damage caused by excess heat.
Explain how guard cells control the rate of water loss in plants
Water loss is controlled by the condition of special cells, called guard cells. These cells regulate the size of microscopic pores in the leaves. These pores are called stomata’s. When the plant has sufficient water, the guard cells shrink. The stomata’s remain closed which preserves the water.
What are the two major sections we divide the eukaryotic cell into?
Nucleus and cytoplasm
What is the cytoplasm?
The portion of the cell outside the nucleus
What does the nucleus contain?
Nearly all the cell’s DNA and with it the coded instructions for making proteins and important molecules.
What is chromatin? What does it form when a cell divides?
The granular material you can see in the nucleus is called chromatin. Chromatin consists of DNA bound to protein. When a cell divides, chromatin condenses to form chromosomes
What does the chromosome contain?
The genetic information that is passed from one generation of cells to the next
What do ribosomes do? What are they?
Small particles or RNA and protein found throughout the cytoplasm. They produce proteins by following coded instructions that come from the nucleus.
What is the endoplasmic reticulum the site of?
The site where lipid components of the cell membrane are assembled along with proteins and other materials that are exported from the cell
What does the rough ER do?
Newly made proteins leave these ribosomes and are inserted into the rough ER, where they may be chemically modified
What does the smooth ER do?
Contains collections of enzymes that perform specialized tasks, including the synthesis of membrane lipids and the detoxifying of drugs.
Into what organelle, do the proteins produced in the rough ER go to next?
The liver cells
What is the function of the Golgi Apparatus? What does it look like?
The function of the Golgi Apparatus is to modify, sort, and package proteins and other materials from the endoplasmic reticulum for storage in the cell or secretion outside the cell
What are lysosomes? What is one function of the lysosomes?
Lysosomes are the small organelles filled with enzymes. One function of lysosomes is the digestion, or the breakdown of lipids, carbohydrates, and proteins into small molecules tat can be used by the rest of the cell.
What can we trace back to lysosomes that fail?
A number of serious human diseases, including Tay-Sachs disease, can be traced to lysosomes that fail to function properly.
What are vacuoles? What types of organisms have vacuoles?
Vacuoles are saclike structures that store materials such as water, salts, proteins, and carbohydrates. Vacuoles are found in some single structured organisms, plants, and animals.
What are mitochondria? What types of organisms have mitochondria?
Mitochondria are organelles that convert the chemical energy stored in food into compounds that are more convent for the cells to use.
Nearly all eukaryotic cells, including plants, contain mitochondria.
Where do humans inherit their mitochondria from?
Nearly all of our mitochondria comes from the cytoplasm of the ovum, or egg cell.
What are chloroplasts? What organisms have these?
Chloroplasts are organelles that capture the energy from sunlight and convert it into chemical energy in a process called photosynthesis.
Plants and some other organisms contain chloroplasts.
What does the cytoskeleton do? What is it also involved in?
The cytoskeleton is a network of protein filaments that helps the cell to maintain its shape.
The cytoskeleton is also involved in movement.
What are the microfilaments made of?
Microfilaments are threadlike structures made of a protein called actin. They form extensive networks in some cells and produce a tough, flexible network that supports the cell.
What are centrioles? What organisms do not have them?
Centrioles are located near the nucleus and help organize cell division.
Centrioles are not found in plant cells.
What is the cell membrane? What does it do?
The cell membrane regulates what enters and leaves the ell and also provides protection and support for the cell.
What is the cell membrane made up of? What does this do for the cell?
Most cell membranes contain protein molecules that are embedded in the lipid bilayer. Some of the proteins form channels and pumps that help to move material across the cell membrane.
What else does the cell membrane contain other than lipids?
Most cell membranes contain protein molecules that are embedded in the lipid bilayer.
What organisms have cell walls? What is the main function?
The main function of the cell wall is to provide support and protection for the cell.
Cell walls are present in many organisms, including plants, algae, fungi, and many prokaryotes.
What is a solution?
Uniform mixtures of two or more substances
What is a solute?
The substances in a solution
What is a solvent?
The substance that the solute is dissolved into
Give an example of a solute and solvent
When salt dissolves in water, the salt is the solute and water is the solvent
What does iso mean?
Equal
What is an isotonic solution?
Provides an environment in which the concentration of solutes outside the cell equals the concentration of the solutes inside
What does hyper mean?
Over
Describe a hypertonic solution
The concentration of solutes outside a cell is greater than the concentration inside
What does hypo mean?
Under
Describe a hypotonic solution
The concentration of solutes outside the cell is less that the concentration inside
