Homeostasis in Organisms

Compare a human and a car…

What is homeostasis? The ability or tendency of an organism or cell to maintain internal equilibrium by adjusting its physiological processes. The ability of an organism or cell to continually monitor and respond to changes in the environment. The maintenance of internal conditions within a narrow range that varies only slightly overtime.

Some examples of homeostasis in humans: Ability to regulate and maintain the necessary amount of water and ions in its cells Regulate and maintain the right amount of glucose in the blood Proper internal body temperature

Dynamic equilibrium The constant small corrections that normally keep the internal environment within the limits needed for survival

Maintaining human body temperature

Responses to Environmental Change

Guard cell activity on the surface of the leaf

Basic Biochemical Processes of Living Organisms The chemical processes that occur in living things. Essential for the organism’s survival. Two of these enzyme-controlled biochemical processes are: - photosynthesis - respiration

Photosynthesis

Photosynthesis can be represented as: light energy+water+carbon dioxide glucose+oxygen light energy + 6H2O + 6 CO2 C6H12O6 + 6O2

Chloroplast in a typical plant cell

Two ways plants use glucose produced from photosynthesis: To generate ATP molecules during cellular respiration Used as raw material for building more complex molecules

Summary of Photosynthesis Energy Materials Used Material Produced Importance The energy comes from sunlight as solar energy and ends up in glucose molecules as chemical bond energy. Carbon dioxide gas and water are used; both molecules come from the environment. Molecules made from the carbon dioxide and water include molecules of the sugar glucose and oxygen gas. Organisms either (1) use glucose to synthesize other molecules they need or (2) break down the glucose to release its stored energy

How much have you learned? Which word equation represents the process of photosynthesis? A. glucose alcohol + carbon dioxide B. carbon dioxide + water glucose + oxygen C. chlorophyll + water glucose + alcohol D. glucose + oxygen carbon dioxide + water

2. The basic raw materials of photosynthesis are A. sugar and carbon dioxide B. oxygen and water C. water and carbon dioxide D. oxygen and sugar

3. In the test tube shown, what is produced by the snail that is used by the plant? A. oxygen B. carbon dioxide C. food D. egg cells

4. In a plant cell, the synthesis of sugar compounds from inorganic raw materials occurs in the A. cell membrane B. mitochondria C. nucleus D. chloroplasts

5. Which activity occurs during the process of photosynthesis? A. Chemical energy from organic molecules is converted into light energy B. Organic molecules are absorbed from the environment C. Organic molecules are converted into inorganic food molecules D. Light energy is stored as chemical energy in organic molecules

6. Which compound is formed as a common product of the process of photosynthesis? A. DNA B. sugar C. chlorophyll D. carbon dioxide

7. Which factor LEAST influences the rate of photosynthesis? A. atmospheric concentration of carbon dioxide B. time of day C. number of chloroplasts D. concentration of nitrogen in the air

Cell Respiration - the process of releasing the energy in chemical bonds Steps: Complex carbohydrate molecules must be broken down (digested) into simpler ones, such as glucose. Glucose (or other simpler molecules) must be broken down further. This process involves a series of chemical reactions controlled by enzymes. Chemical bonds of the glucose molecules are broken, and their energy released.

Materials used Materials produced Importance Energy Materials used Materials produced Importance Comes from the chemical bond energy of glucose molecules; ends up in ATP bonds where it can be utilized for cell activities Sugar or other energy-rich organic food compounds and oxygen gas from the environment. Oxygen is obtained through gas exchange. ATP molecules and two waste products-carbon dioxide gas and water. The release of oxygen is part of gas exhange. All cells “run” on the energy released from ATP. The energy is also used to allow the organism to grow and move from one place to another.

catalyst - any substance that can affect the rate of a chemical reaction without itself being changed or used up during the reaction enzymes - protein catalysts that affect the chemical reactions in living things

Functions of enzymes: Enzymes make possible biochemical processes such as digestion, synthesis, cellular respiration, and photosynthesis Enzymes regulate chemical reactions in living organisms.

Importance of Molecular Shape

Conditions that affect rate of enzyme action Shape chain-like molecules that are folded into precise shapes must have specific shape to work correctly Temperature have an optimum temperature at which they function most efficiently and produce the highest rate pH Many enzymes work best in an optimum pH of about 7

Enzyme and Temperature

Enzyme and pH

How much have you learned? In which process do organisms transfer the chemical bond energy in organic molecules to ATP molecules? A. excretion B. cellular respiration C. autotrophic nutrition D. photosynthesis

2. The process during which energy is released from digested foods is called A. cellular respiration B. chemical digestion C. photosynthesis D. excretion

3. Which process involves the transfer of energy from carbohydrates to ATP molecules? A. photosynthesis B. respiration C. digestion D. circulation

enzyme H2O + ATP ADP + P + energy 4. Which statement best describes one of the events taking place in the chemical reaction represented below? enzyme H2O + ATP ADP + P + energy A. Energy is being stored as a result of cellular respiration. B. Energy is being released for metabolic processes. C. Decomposition is taking place, resulting in the synthesis of ATP. D. Photosynthesis is taking place, resulting in the storage of energy.

5. Energy for use in cells is stored in the form of A. chemical bond energy B. physical energy C. heat energy D. mechanical energy

6. Energy released from the cellular respiration of glucose is A. first stored within ATP B. stored in the liver as fat C. turned into fat D. used directly for body activity

7. As a direct result of the life process called cellular respiration in humans, A. liquid wastes are eliminated from the body B. food is digested and absorbed into the blood C. energy is released from digested food within the cells D. nutrients are transported within the cells

8. During respiration, the energy within the bonds of a glucose molecule is released in small amounts in a step-by-step, enzyme-controlled reaction. In this process, the energy released is used to A. synthesize ATP B. control the process of diffusion C. synthesize more glucose D. produce oxygen molecules

9. The process represented in the diagram below is A. respiration B. coordination C. photosynthesis D. immunity

10. What term would most appropriately be represented by the “X” in the diagram below A. chlorophyll B. ATP C. antibodies D. glucose

11. Only small amounts of enzymes are required for reactions within cells because enzymes are A. fragile B. reused C. small molecules D. constantly synthesized

12. Which group of organic compounds includes the enzymes? A. proteins B. carbohydrates C. sugars D. starches

13. The enzyme salivary amylase will act on starch but not on protein 13. The enzyme salivary amylase will act on starch but not on protein. This action illustrates that salivary amylase A. contains starch B. is chemically specific C. is not reusable D. lacks protein

14. A particular human intestinal enzyme is most active at a pH of 8 14. A particular human intestinal enzyme is most active at a pH of 8.0 and a temperature of 37ºC. The activity of this enzyme would most likely decrease with an increase in the A. amount of light shining on the reaction B. amount of enzyme C. amount of substance being acted on D. temperature to over 50ºC

15. Enzymes influence chemical reactions in living systems by A. becoming part of the product after the reactions occur B. combining with atmospheric gases to form waste products C. affecting the rate at which reaction occur D. absorbing water during synthesis and digestion

Feedback Mechanisms