What structure prevents food from entering the respiratory system when swallowed?
A flap of skin called the epiglottis closes over the trachea to prevent food entry
What are the two types of vascular tissue responsible for transport in plants?
The two types of vascular tissue are xylem and phloem
What are the microscopic projections in the small intestine that increase the surface area for nutrient absorption?
These tiny projections are called villi
How do gases reach the cells of an insect without the use of a blood transport system?
Air enters the spiracles and is drawn into a network of branching tracheal tubes (and smaller tracheoles), bringing air directly to and from the cells
What are lenticels?
Lenticels are pores through which gaseous exchange occurs in the woody parts of plants, like tree trunks and branches
How do root hair cells improve the efficiency of a plant's water absorption?
Root hairs are microscopic extensions that increase the surface area of a root up to 12 times, allowing for much greater absorption
What specialized gas exchange structures do fish use to extract oxygen from water?
Fish possess gills, which extract oxygen as water flows over them
By what process does oxygen move from the alveoli into the surrounding bloodstream?
Oxygen moves by diffusion across a concentration gradient
What is the main function of the phloem?
Phloem transports sugars, in the form of dissolved sucrose, and other plant products from one part of the plant to another
Which cells in the leaf's mesophyll are the main sites for photosynthesis?
Palisade cells, which are elongated and dense with chloroplasts, are the main photosynthetic cells, followed by spongy mesophyll cells
What is the primary function of the xylem?
Xylem is responsible for transporting water, water-soluble nutrients, and minerals absorbed from the soil through the root system
What are the two types of digestion that occur in the mammalian digestive system?
Digestion is broken down into mechanical digestion and chemical digestion
What are the breathing pores that insects use to take in and expel air?
Insects use structures called spiracles
Which structures control the opening and closing of the stomata?
Stomata are bordered and controlled by two bean-shaped guard cells
Where is bile produced, and where is it stored?
Bile is produced by the liver and is stored in the gall bladder
What is the function of bile in the digestive process?
Bile emulsifies (breaks down) fats into smaller droplets to increase their surface area so the digestive enzyme lipase can chemically break them down
Through the use of radioisotopes, scientists discovered that the oxygen released during photosynthesis comes from which molecule?
It was shown that water (not carbon dioxide) is the source of the oxygen gas released
What are the pores on a leaf's surface that allow for the exchange of gases?
These pores are called stomata (or stomates)
Which essential gas is required by autotrophs for photosynthesis, but is not required by heterotrophs?
Carbon dioxide gas
Which active enzyme in the stomach begins the chemical breakdown of proteins?
Pepsin, which is converted from pepsinogen in an acidic environment, breaks down long-chained proteins
What occurs in the large intestine during the final stages of mammalian digestion?
In the large intestine, water, salts, and vitamins A and K are absorbed back into the bloodstream, and the remaining undigested material is compacted into a sol
Which enzyme in the mouth begins the chemical breakdown of the complex carbohydrate starch?
The enzyme salivary amylase begins breaking down starch into the simpler sugar maltose
What are the specialized gaseous exchange surfaces located in the mammalian lungs?
These thin-walled air sacs are called alveoli
What is the process of muscular contractions that moves food down the oesophagus?
This process is called peristalsis
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