Higher Biology Adaptation Part 1

2 Adaptation 1 By the end of this lesson you should be able to:  Understand osmoregulation in freshwater and saltwater fish.  Know the differences between them in terms of number and size of glomeruli, filtration rate and chloride secretory cells.  Know how the salmon copes with 2 different environments.

3 Introduction  An adaptation is a characteristic possessed by an organism which gives it an advantage in a particular environment.  Many adaptations have evolved over a very long period and have been selected for, to enable the organism to survive.  There are three categories of adaptations: structuralphysiologicalbehavioural

4 Introduction  Over the next few lessons you are going to be studying the following adaptations:  Freshwater fish  Saltwater fish  Migratory fish  Desert mammals  Plants that live in deserts  Plants that live in water

5 Osmoregulation  Osmoregulation is the process of controlling the water and ion (salt) balance of the body.  In humans: The organs of osmoregulation are the kidneys The hormone involved is called ADH- Anti Diuretic Hormone. Insert and complete “The Kidney” revision sheet from your pack into your notes.

6 Osmoregulation  Can you remember the following terms? 1. Isotonic 2. Hypertonic 3. Hypotonic 4. Osmosis  What problems will fish that live in freshwater face?  What problems will fish that live in saltwater face?

7 Freshwater bony fish  Live in……… conditions  Water tends to the fish by osmosis.  So the fish has to get rid of excess water, but at the same time, not lose essential salt ions. Hypotonic/hypertonic/isotonic enter/leave

8 Freshwater fish How do they do it? 1. They do not drink 2. They have many, large glomeruli high filtration rate of substances from the blood. 3. This produces a large volume of dilute urine (containing ammonia)

9 Freshwater fish How do they do it? 4. The nephrons are very efficient at reabsorbing salts from the filtrate back into the blood. 5. Their gills contain cells called chloride secretory cells which actively take up sodium and chloride ions into their blood from the water they live in. Complete the “Freshwater fish” diagram from your diagram pack.

10 Saltwater bony fish  Live in……… conditions  Water tends to the fish by osmosis.  So the fish is constantly losing water through their gills and gut membranes. Hypotonic/hypertonic/isotonic enter/leave

11 Saltwater fish How do they do it? 1. They drink sea water to replace lost water 2. They have few, small glomeruli low filtration rate of water from the blood. 3. This produces a small volume of urine containing a non-toxic nitrogenous waste.

12 Saltwater fish How do they do it? 4. Their gills contain cells called chloride secretory cells which actively excrete sodium and chloride ions (gained by drinking sea water) out of their blood and into the water they live in. Complete the “Saltwater fish” diagram from your diagram pack.

13 Migratory fish  These migrate between fresh and salt water so have the problems of both freshwater and salt water fish! How do they do it? You find out!

14 Migratory fish  Use Torrance pages to find out: What changes occur in the salmon when it moves from fresh water into sea water and vice versa in terms of: 1. Hormones 2. Filtration rate 3. Chloride secretory cells NB the eel faces the same problems!

15 Practice Questions  Torrance 1. TYK page 171 Q1-3

16 Adaptation 1 Can you do it?  Understand osmoregulation in freshwater and saltwater fish.  Know the differences between them in terms of number and size of glomeruli, filtration rate and chloride secretory cells.  Know how the salmon copes with 2 different environments.