شرح علوم متكاملة لغات الصف الاول الثانوي لغات - الفصل الدراسي الأول
شرح علوم متكاملة اولي ثانوي لغات - ترم أول
Integrated Sciences for Grade 10 (First Year of Secondary School) - First Semester
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In This Lesson :
Biological adaptations
Examples
1. Some deep ocean fish have special abilities to regulate respiration under the state of oxygen deficiency.
A famous example is the Electric Eel, which lives at depths of thousands of meters, where oxygen levels are extremely low. These fish have developed very large gills, with very fine capillaries that maximize the efficiency of extracting the little oxygen found in water. In addition, they can slow down their metabolism to minimize their oxygen needs.
2. Deep-sea fish have strong and durable arteries and veins that can withstand the high pressure to adapt to the high-water pressure at great depths.
Osmosis and osmotic pressure
Osmosis is the phenomenon of water transfer from a dilute solution to a concentrated solution through a semi-permeable membrane separating the two solutions as shown in the figure.
Osmotic pressure is the pressure created in a solution due to the difference in solute concentration in the solution and leads to the diffusion of water from the less concentrated solution (low osmotic pressure) towards the more concentrated solution (higher osmotic pressure).
Physiological adaptations of freshwater organisms to low osmotic pressure
Unicellular organisms, such as amoeba, paramecium, and euglena, have a structure or an organelle called a contractile vacuole that collects excess water in the cell and when it is filled with water, it moves towards the cell membrane where it discharges its water content to the outside of the cell.
Multicellular organisms, such as fish, eliminate excess water that enters the body through the skin, mouth, and gills by the kidneys in the form of dilute urine. In fish, the kidneys are located in the abdominal cavity on either side of the spine.
While fish that live in saltwater need to swallow large amounts of sea water to compensate for the osmotic loss of water from their body, and then they excrete excess salts through their kidneys and specialized cells in their gills.
Behavioral adaptations
Behavioral adaptations include certain actions or behaviors that organisms use to avoid extreme conditions or to better utilize available resources. For example, some fish migrate between fresh and salt water to reproduce and survive.
Salmon are born in freshwater, then move to the sea where they spend most of their adult life, before returning to rivers again to reproduce. When salmon eggs hatch, their young spend the first period of their lives in freshwater. During this stage, the youngsters adapt to the freshwater environment. Upon reaching a certain size, the fish undergo a biological process known as “Smoltification” which allows them to move to the saltwater of the sea. When salmon reach sexual maturity, they begin to return to the rivers where they were born to reproduce.
Structural adaptations
Structural adaptations include changes in the physical structure of organisms that help them survive in their environments. For example, fish that live in the deep ocean have very large eyes to be able to see in the dark, and their bodies are compressed to withstand the very high pressure in deep water. An example of a compressed deep-sea fish is the icefish, which lives in the cold southern oceans, at depths of about 2000 meters.
Among the general structural adaptations of fish are a streamlined body that reduces water resistance to the fish's movement, gills that enable it to extract dissolved oxygen in water, and its body is covered with scales and mucus to be waterproof and to reduce water resistance to its movement, fins are movement organs, and bony fish have an air bladder or swim bladder that helps them float in the water.
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