Animal_form_and_function

Animal_form_and_function - Chapter 40: Animal form and...

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Chapter 40: Animal form and function
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Characteristics of animals Lots of variation in form, but ALL animals Require oxygen and nutrients Must fight infection Reproduce
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Overview: Diverse Forms, Common Challenges Anatomy - study of the form of an organism Physiology - study of the way an organism functions. Form and function are closely correlated. Natural selection favors forms that best meet functional needs.
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Evolution via natural selection allows organisms to meet challenges of a specific environment Arctic environment = endotherm, camouflage Aquatic = gills (usually), streamlined body shape
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Size and shape There is lots of variation in body plans, but physical laws govern strength of materials, diffusion, movement of particles, and heat exchange.
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Size and shape Water and air have specific properties that may affect how the organism functions (survives) in its habitat.
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The scale of life Organisms can be large or small, but this also affects how they function.
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The surface area to volume ratio or: why size matters Size is related to both surface area and volume. Volume determines the amount of chemical activity (resource use, waste produced) in the cell per unit time. Surface area determines the amount of materials that can cross the cell boundary per unit time.
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The surface area to volume ratio or: why size matters Surface area does not increase as rapidly as volume. As size goes up, chemical activity (related to volume) increases faster than the ability of the cell to move materials across its membrane (related to surface area). Many small cells work more efficiently than one large cell.
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The scale of life Regardless of size or number of cells, every cell must be able to carry out its functions (receive nutrients, eliminate wastes, gas exchange). This means each cell must somehow be in contact with the environment.
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Exchange 0.15 mm (a) Single cell 1.5 mm (b) Two layers of cells Exchange Exchange Mouth Gastrovascular cavity At small sizes (one or two layers of cells), simple diffusion works very well. But what happens when size increases beyond this?
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Nutrients Mouth Digestive system Anus Unabsorbed matter (feces) Metabolic waste products (nitrogenous waste) Excretory system Circulatory system Interstitial fluid Cells Respiratory system Heart Animal body CO 2 O 2 Food External environment Lots of folds in the surface membranes increase surface area to facilitate exchange of wastes, gasses and nutrients Larger, multicellular organisms use a vascular or circulatory system.
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Nutrients Digestive system Lining of small intestine Mouth Food External environment Animal body CO 2 O 2 Circulatory system Heart Respiratory system Cells Interstitial fluid Excretory system Anus Unabsorbed matter (feces) Metabolic waste products (nitrogenous waste) Kidney tubules 10 μm 50 μm Lung tissue As organisms have more cells, groups of cells specialize, which makes tissues. Groups of tissues make organs.
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Animal_form_and_function - Chapter 40: Animal form and...

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