1. Lecture Presentations by Carol R. Anderson Westwood College, River Oaks Campus © 2014 Pearson Education, Inc. BIOLOGY Life on Earth WITH PHYSIOLOGY Tenth Edition Audesirk Audesirk Byers 1 An Introduction to Life on Earth

2. © 2014 Pearson Education, Inc. Chapter 1 At a Glance What Is Life?

3. © 2014 Pearson Education, Inc. 1.1 What Is Life? Biology comes from the Greek words “bio” meaning “life” and “logy” meaning “the study of.” Organisms share common characteristics that, taken together, define life. Organisms:  Acquire and use materials and energy  Actively maintain organized complexity (made of cells)  Perceive and respond to stimuli  Grow  Reproduce  Have the capacity to evolve, collectively  Homeostasis

4. © 2014 Pearson Education, Inc. 1.1 What Is Life?  The cell is the basic unit of life –It is separated from its surroundings by a membrane –It encloses a variety of structures and chemicals in a fluid environment

5. © 2014 Pearson Education, Inc. Figure 1-1 The cell is the smallest unit of life organelles nucleus cell wall plasma membrane

6. © 2014 Pearson Education, Inc. 1.1 What Is Life?  Organisms acquire and use materials and energy –Materials and energy are required for organisms to maintain organization, to grow, and to reproduce –Important materials (minerals, water, & other simple chemical building blocks) are acquired from the air, water, soil, and bodies of other living things –Organisms use energy continuously to sustain themselves

7. © 2014 Pearson Education, Inc. Figure 1-2 Properties of life Eggs: living things reproduce Gut: living things acquire nutrients Antennae and eyes: living things respond to stimuli

8. © 2014 Pearson Education, Inc. 1.1 What Is Life?  Organisms acquire and use materials and energy (continued) –Organisms obtain energy in two ways, coming directly or indirectly from the sun –Photosynthesis is the process by which plants and some single-celled organisms capture sunlight –Other organisms consume energy-rich molecules in the bodies of other organisms

9. © 2014 Pearson Education, Inc. Figure 1-3 The flow of energy and the recycling of nutrients

10. © 2014 Pearson Education, Inc. 1.1 What Is Life?  Organisms actively maintain organized complexity –Living things use energy on a continuous basis to self-sustain –Cells pump chemicals in and out for appropriate chemical reactions to occur –Organisms maintain relatively constant internal conditions or homeostasis

11. © 2014 Pearson Education, Inc. Figure 1-4 Organisms maintain relatively constant internal conditions

12. © 2014 Pearson Education, Inc. 1.1 What Is Life?  Organisms perceive and respond to stimuli and maintain homeostasis –Organisms sense and respond to internal and external environmental stimuli –Sensory organs in animals can detect and respond to external stimuli such as light, sound, chemicals, etc. –Internal stimuli in animals are perceived by stretch, temperature, pain, and chemical receptors –Plants and bacteria respond to stimuli as well (e.g., plants grow toward the light, and bacteria move toward available nutrients in a medium)

13. © 2014 Pearson Education, Inc. 1.1 What Is Life?  Organisms grow –Every organism becomes larger over time –Plants, birds, and mammals grow by producing more cells to increase their mass –Bacteria grow by enlarging their cells; they divide in half to reproduce after genetic material is copied –Growth involves the conversion of acquired materials to molecules of the organism’s body

14. © 2014 Pearson Education, Inc. 1.1 What Is Life?  Organisms reproduce –Organisms reproduce by dividing in half, producing seeds, bearing live young, and laying eggs –Organisms give rise to offspring of the same type –The parent’s genetic material (DNA) is passed on to the offspring, creating continuity of life

15. © 2014 Pearson Education, Inc. Figure 1-6 Organisms reproduce Dividing Streptococcus bacterium Panda with its baby Dandelion producing seeds

16. © 2014 Pearson Education, Inc. Figure 1-7 DNA

17. © 2014 Pearson Education, Inc. 1.1 What Is Life?  Organisms, collectively, have the capacity to evolve –Evolution is the process by which modern organisms descended, with modifications, from preexisting forms of life –Changes in DNA within populations occur over the course of generations, which results in evolution –Populations are groups of the same type of organism living in the same area

18. © 2014 Pearson Education, Inc. 1.2 What Is Evolution?  Evolution explains the diversity of life on Earth  Evolution provides an explanation for the similarities found among different types of organisms –Chimpanzees and people have various physical features in common –DNA of humans differs from that of chimpanzees by less than 5%

19. © 2014 Pearson Education, Inc. Figure 1-8 Chimps and people are closely related