Prepared by Mike Comet!

2. Homeostasis: _______________________________________________________________

3. Failure to maintain homeostasis results in ______________ or ____________________

4. Homeostasis is often maintained using ______________________ mechanisms.

5. Feedback mechanisms are cycles in which the product of one reaction causes another to start or stop.

6. While organisms are balanced, they are not unchanging. The term used to describe the balanced state is dynamic equilibrium.

7. Dynamic Equilibrium: A balanced state created by many small, opposing changes.

8. Life Processes: All living things carry out the same basic chemical processes. Taken together, these process make up an organism’s __________________________.

9. Metabolism: _______________________________________________________________

10. ____________________: Using nutrients for growth, synthesis, repair and energy.

11. ____________________: Converts energy in food into a usable form (ATP).

12. ____________________: Making complex chemicals from simple substances.

13. ____________________: Absorbing and distributing materials throughout the body.

14. ____________________: The control and coordination of life processes.

15. ____________________: Removing of wastes produced by metabolic activities.

16. ____________________: Passes on genes to offspring.

17. Inorganic Chemicals: Simple compounds

18. Water ( _____) : Most common substance in all living things (about 60% of body mass)

19. Needed for chemical reactions (won’t happen in “dry” conditions)

20. Dissolves other molecules into solution, allowing them to be transported through the body.

21. Oxygen (______): Needed by most (not all) organisms for cellular respiration.

22. Released by plants and algae as a waste product of _________________________.

23. Aerobic respiration: Process that uses oxygen to extract energy from glucose (sugar). Used by most organisms.

24. Anaerobic respiration: Process that extracts energy from glucose without using oxygen. Gives less energy, so only used by some simple organisms (some bacteria, yeast). These organisms do not need to breathe in oxygen.

25. Carbon Dioxide (______): With water, used by plants to make glucose (photosynthesis).

26. Waste product of aerobic respiration.

27. Nitrogen (_____): Most common gas in air (70%)

28. Needed to make protein.

29. Converted into ______________ by soil bacteria. Nitrates are absorbed by plants and then eaten by animals.

30. Excreted as waste in _________________ or __________________.

31. Acids and Bases: Used for different functions in body (such as digestion).

32. Measured by the pH scale

33. Very high and very low pHs are usually lethal.

34. pH can affect rates of chemical reactions; for example, digestive enzymes work fastest in acidic environments, which is why we make stomach acid (hydrochloric acid, or HCl).

35. Organic Compounds: Larger, more complex chemicals. Always contain the elements carbon (C)and hydrogen (H). Synthesized from simpler substances (building blocks).

36. Carbohydrates: ___________________________________

37. Building blocks:5607050-27940 _____________________

38. Functions:

39. _________________

40. A starch (A) is broken down by an enzyme (B) into two simple sugars (C, D). This is also a good example of the lock and key model._________________ (starch)

41. Lipids: _________________________________________

42. Functions:

43. _________________

44. _________________

45. _________________

46. _________________

47. Proteins: Complex compounds that carry out all the body’s activities.

48. Building blocks: _________________

49. After water, proteins are the most plentiful substances in the body.

50. Have many different functions as determined by their ___________.

51. Lock and Key Model: Proteins must have the right shape to “fit” with other molecules.

52. Changing the shape of a protein will change what it can interact with its function.

53. Important types of proteins:

54. Hormones and neurotransmitters – carry messages through the body.

55. Cell receptors – in cell membrane; receive hormones and neurotransmitters.

56. Antibodies – attack foreign pathogens

57. Enzymes- act as catalysts, controlling all chemical reactions in the body.

58. High temperatures will cause enzymes to denature (lose their shape) and stop functioning. This is why high fevers are dangerous.

59. Nucleic Acids (DNA and RNA): Make up genes and chromosomes.

61. Cell Theory has three parts:

62. _______________________________________________________________________

63. Unicellular – single celled organisms (amoeba, paramecium)

64. Multicellular – have more than 1 cell; may be only a few (vorticella), or many trillions of cells (humans). Almost all structures in multicelled organisms are made of or by cells.

65. _______________________________________________________________________

66. Everything you do is the result of the work of your cells – walking, talking, even thinking and feeling. When you get sick, it is because your cells are not working correctly.

67. _______________________________________________________________________

68. This seems obvious now, but at one time people believed in spontaneous generation, the idea that living things regularly emerged from nonliving things.

69. Exceptions to the Cell Theory

70. ________________ are not made of cells. However, they also do not carry out all life processes, so many biologists do not consider them true living things.

71. ____________________ obviously could not come from another cell.

72. Organization

73. 5124450114300Cell Organelles: These are the tiny cell parts that make up a cell.

74. ___________________

75. Controls the cell

76. Contains hereditary material (chromosomes, genes, DNA)

77. ______________________

78. Fluid/liquid in the cell – mostly water

79. Helps transport material

80. _______________________

81. Carries out cellular respiration.

82. Gives cell energy (Powerhouse of the cell).

83. _______________________

84. Makes proteins from amino acids.

85. ________________________

86. Stores food, water and waste

87. Food vacuoles may digest large molecules.

88. Waste vacuoles may excrete waste out the cell membrane

89. _______________________

90. Carries out photosynthesis

91. Plant and algae cells only

92. _______________________

93. Gives shape, structure and protection.

94. NEVER found in animal cells.

95. ________________________

96. Separates cell interior from environment

97. Controls what enters and leaves the cell using _______________ ________________.

98. Has ___________________ ____________________ that pick up signals from other cells.

100. _______________________

101. _______________________

102. _______________________

103. _______________________

104. Ingestion: ______________________________________________________

105. Digestion: ______________________________________________________

106. Nutrients must be broken down into smaller parts so that they can be ________________ into the blood and cells of organisms.

107. Starches are digested into __________________.

108. Proteins are digested into ___________________.

109. Autotrophic Nutrition: Organisms take ______________________ materials (______, ______) and convert them into organic nutrients (__________________).

110. Auto = _________ ; troph = ____________ so Autotroph = _______________________

111. ______________________ is most common form of autotrophic nutrition

112. Ex: _____________________________________

113. Heterotrophic Nutrition: Organisms must __________________ nutrients made by other organisms.

114. Hetero = ___________, so Heterotroph = ___________________________.

115. All _____________________ and _______________ are heterotrophs.

116. Includes:

117. Carnivores: _____________________________________

118. Herbivores:_____________________________________

119. Ominivores:_____________________________________

120. Decomposers:___________________________________

121. Photosynthesis: Process in which sun’s energy is trapped in the chemical ________ of sugar.

122. Requires _________________, ________________ and __________________.

123. Makes ___________________ (_________________) as food.

124. ____________________ and ________________ are waste products.

125. Benefits:

126. Provides food for all plants, animals and other organisms.

127. Provides _____________ to breathe.

128. Removes _______ from atmosphere.

129. Plant adaptations:

130. Chloroplast: Cell organelle that does photosynthesis

131. Gas exchange:

132. Stomates : __________ under a leaf; let gases in and out

133. Guard cells: open and close stomates to prevent _________________________

134. Transport:

135. Xylem and Phloem: “tubes” transport food and water throughout the plant.

137. ______ is the molecule all life uses for energy.

138. No organism can get energy from sunlight or sugar without first putting the energy into ATP.

139. Requires _________________, ________________ and __________________.

140. ____________________ and ________________ are waste products.

141. Most organisms carry out aerobic respiration (uses oxygen) in their mitochondria.

142. Anerobic respiration does not require oxygen, but gives less ATP (energy) for each molecule of sugar.

143. 6096000403225When exercise causes human muscles to run out of oxygen, their cells will do anaerobic respiration. The waste product, lactic acid, causes muscles to “ burn” so that you will stop.

144. Photosynthesis and Cellular Respiration are opposite reactions! They are also important in cycling oxygen, carbon, hydrogen and water through the environment

145. Common mistakes:

146. “Plants use photosynthesis, animals use respiration.”

147. All organisms, including plants, use respiration to get their energy.

148. “Respiration is breathing.”

149. Breathing is not respiration. Breathing exchanges the gases needed for respiration. Inhaling and exhaling does not give you ATP.

150. “Oxygen is used to breathe.”

152. All humans (and most other organisms) begin life as a ______________ cell.

153. This single cell is called a ___________________.

154. The nucleus of this cell has _________ the genes needed to become a complete organism.

155. Humans grow as a result of ______________(cell division).

156. This quickly increases the number of cells in the body until there many trillions of cells.

157. Since all new cells come from the same single cell, they all share the same __________.

158. As cells divide, they begin to develop into specialized tissues.

159. Specialization or Differentiation: Process in which a cell changes to have a special shape and function.

160. 584835047625Cells specialize by turning specific genes on or off.

161. Ex: A white blood cell has turned off all genes needed to make skin, bone, or nerves. It still has those genes, but only the genes needed to be a white blood cell remain turned on.

162. As the body continues to develop, tissues will work together to form ____________ .

163. Two neurons carry an impulse to a muscle cell. (3) shows where a neurotransmitter would carry the signal from one cell to the next.Organs will work together to form ______________ ____________________ .

164. Org an systems will work together to help a person maintain homeostasis.

165. Nervous System

166. The nervous system __________________ your body with electrochemical ______________.

167. The chemical portion of a nerve impules is called a ____________________________

168. Neurotransmitters released by 1 nerve cell are received by _______________________ _______________________ in the cell membrane of the next nerve cell.

169. The shape of the receptor molecule determines which neurotransmitter it can receive.

170. A nerve cell is also called a ___________________.

171. The main organs of the nervous system are the ___________ and ___________________

172. The spinal cord controls reflexes and relays impulses between the brain and body.

173. Endocrine System

174. 685800041910Uses _________________ to regulate the body.

175. A hormone is a chemical ___________________ secreted by endocrine glands.

176. Hormones are slower than nerve impulses, but with longer lasting effects.

177. Hormone levels are controlled by feedback mechanisms.

178. 107632535560

179. A feedback mechanism

180. Receptor Molecules in the cell membrane can only accept molecules of the correct shape. This is a good example of the Lock and Key Model.Receptor molecules on the surface of the cell membrane receive hormones. As with all proteins, it is the shape of the receptor molecule that determines which hormone it can receive.

181. The _________________ makes ______________ and glucagon which control blood sugar.

182. Common mistake: “Insulin lowers blood pressure.”

183. Insulin (and glucagon) directly control blood sugar (or glucose) levels, not blood pressure.

184. Adrenal glands make adrenaline when the body is under stress.

186. _________________ and ________________from intestines to all cells of body.

187. _________________ from lungs to all cells of the body.

188. _________________ from glands to target cells

189. _________________ from all cells to the excretory organs.

190. Materials usually enter and leave the blood through diffusion.

191. Diffusion: Process in which material moves from a high concentration to a low concentration.

192. Ex: There is a high concentration of oxygen in the lungs, so oxygen will diffuse from the lungs into the blood, which has less oxygen.

194. ______________ is the fluid of the blood. It transports everything except oxygen.

196. 6009005-73025The job of the immune system is to protect the body against ___________________.

197. Pathogen: ____________________________________________________________.

198. Types of pathogens include viruses, bacteria, and parasites.

199. White Blood Cells are the main components of the immune system.

200. Different w.b.c’s have different roles, including:

201. Identify pathogens

202. “Tag” pathogens for destruction by other wbc’s.

203. Destroy pathogen by eating it.

204. Destroy pathogen using chemicals

205. Make antibodies

206. Antibodies are _______________made by white blood cells to attack pathogens.

207. Every antibody is specific in its action – it can attack one and only one type of pathogen. As with all proteins, this is because the shape of the antibody must fit its target (lock and key model).

208. An immune response – white blood cells and antibodies attack a virus.Antigens are protein “tags” that identify a cell or virus.

209. Your blood type is determined by your antigens (you can have A or B antigens, both or nether (type O).

210. Any cell of virus with the wrong antigen will be seen as foreign by your immune system, attacked, and destroyed. This is why you must match blood types before receiving blood or an organ transplant.

211. A ___________________ is an injection of a dead or weakened pathogen.

212. Triggers the body to make antibodies against that pathogen.

213. Effective against both viruses and bacteria.

214. Can only prevent disease, not cure it.

215. ____________________ are drugs used to stop infections by bacteria.

216. Antibiotics will not work against viruses.

217. Unlike vaccines, antibiotics can cure diseases.

218. Common mistake:

219. “Antibodies are cells that attack pathogens.” Antibodies are proteins, not cells.

220. Interactions between body systems

221. The different systems of the body work together to maintain homeostasis. For example:

222. Nutrients from the _________________ system are transported to cells by the __________________ system.

223. Wastes from the _________________ system are removed by the _______________ system.

224. The ___________________ and __________________ systems work together to control the body.

225. The ___________________ system protects the ________________ system from disease.

227. Humans have ______ chromosomes, or ______ homologous pairs.

228. Homologous: ______________________________________________________

229. Chromosome pairs carry genes for the same traits.

230. Most organisms have two genes for each trait - 1 from each parent, 1 on each member of the homologous pair.

231. Sex chromosomes – In humans, females are ______ and males are ______.

232. The Y chromosome is much _____________ than the X, so it is missing many genes. This means many genes on the X chromosome do not have a “partner” so:

233. If a male has a recessive trait on the X chromosome, the Y chromosome will not be able to “hide” it with a dominant gene, so...

234. This makes males more likely to have some traits (like color blindness). These are called sex linked traits.

235. Common mistake: “Humans have 23 chromosomes (or 46 pairs of chromosomes, or some other incorrect number).”

236. These numbers are often confused. You must memorize them correctly.

237. Chromosomes and Genes

238. Each chromosome has hundreds or thousands of genes.

239. Each gene codes for a particular protein.

240. Common mistake: “Genes/DNA are made from protein.”

241. Genes carry the instructions to make protein. The genes themselves are made from nucleic acids.

242. While genes determine our traits, the environment can affect expression of genes.

243. 594995070485DNA

244. DNA is the chemical that makes up your genes and chromosomes.

245. Analogy: If your genes and chromosomes are the “instruction manual” for your body, DNA would be the paper it is printed on.

246. The shape of a DNA molecule is a_______________________, which resembles a twisted ladder.

247. The shape of DNA allows it to _________________________ (copy) itself almost perfectly.

248. DNA is made of 4 bases: ____________________.

249. Base pairs: _________ and __________

250. in RNA the pairs are __________ and ____________

251. Protein Synthesis: This is how genes control your body:

252. A codon is a sequence of __________bases in DNA.

253. Each codon represents a specific amino acid.

254. 569595053340______________________ assemble amino acids in the same order that they are listed in the DNA codons.

255. The amino acids will make a __________________.

256. The order of the amino acids (determined by the DNA sequence) determines the _____________ of the protein.

257. The shape of a protein determines its _____________________.

258. Therefore: The sequence of bases in DNA will determine the ____________________ of all the proteins in the body.

259. The proteins build and run the body.

261. Can only be passed on if they occur in reproductive cells (sperm or egg).

262. Common mutagenic agents include ____________________________________________.

263. Mutagenic agent: ________________________________________________________.

264. Gene mutations may cause a change in a gene which can change the __________ of a ___________. This will have an effect on the way the protein works (if it still works at all).

265. Gene mutations are caused when DNA bases are in some way changed.

266. Chromosome mutations are usually caused when a person inherits too many or too few chromosomes.

267. Chromosome mutations affect many genes at once. Most are lethal

268. Down’s Syndrome: Non lethal mutation, caused by inheritance of an extra copy of chromosome 21. (Note – only chromosome 21 can cause Down Syndrome).

269. Genetic technology:

270. Selective breeding:__________________________________________________________ __________________________________________________________________________

271. Ex:

272. 528510571755Genetic engineering: ________________________________________________________ __________________________________________________________________________.

273. ____________________are used to cut and paste the DNA segments.

274. Organism that receives the new gene will begin to make the _______________, ___________________ or _______________________ coded for by that gene.

275. The new protein/enzyme/hormone will be ___________________________________ as the one produced by the original organism.

276. _________________are often used because they are simple and reproduce quickly.

277. The example of gene splicing you MUST know:

278. Bacteria have been engineered to make ______________________ fo r diabetics.

279. Bacteria have been engineered to make ________________________________.

280. In both cases the engineered hormones are safe to use because they are identical to normal human hormones.

281. New technologies (karyotyping, DNA fingerprinting) are making it easier to diagnose and treat genetic disease, though we cannot yet cure them.

282. Karyotype: A photograph of an organism’s chromosomes.

283. Can determine if a person has a chromosome disorder such as Down Syndrome.

284. DNA finerprinting, or gel electrophoresis, creates banded patterns based on a person’s DNA base sequence.

285. Each fingerprint is unique, so it can be used to identify people.

286. Fingerprints of relatives are similar to each other, so can be used to determine genetic relationships between two people, or even two groups of organisms.

287. Genetic research has posed many ethical problems (ie right and wrong) that science alone cannot answer.

289. Modern Theory of Evolution:

290. Charles Darwin:

291. Was not the first to think of evolution, but he did figure out how it works (mostly).

292. Darwin didn’t know about genes, so he couldn’t know about mutations.

293. The modern theory (which combines Darwin’s ideas with genetics and other new ideas) contains the following ideas:

294. Earth is old (4.55 billion years) and is constantly changing.

295. As the environment changes, evolution causes species to adapt to their environment.

296. ______________________________________ is the mechanism that causes species to change.

297. Common Descent: Modern species evolved from earlier, different species and share a common ancestor.

298. Species that can not adapt become _____________________.

299. New traits arise in a species from ___________________________ and _____________________________________________.

300. Environment and Evolution: Species usually evolve when the environment changes.

301. Changes need to be long term – species do not evolve because of changes in the season.

302. Changes can include:

303. Climate change

304. Change in temp

305. Change in water availability

306. Change in food availability

307. Introduction of new species (new food, new predator)

308. Species may be moved to a new location (accidentally taken to an island for example)

309. Environmental change DOES NOT CAUSE evolution to occur. A temperature or climate change does not itself force a species to change its inherited characteristics.

310. If this were the case, then all species would be able to adapt to the new environment, and extinction would be a very rare event.

311. Natural Selection: The basic steps in natural selection are:

312. __________________________________: Members of a species are different from each other due to mutations and sexual reproduction.

313. No variation = no evolution or natural selection, as there is nothing to “select.”

314. Species with no variation are usually the first to die when the environment changes.

315. ___________________________________: Too many offspring are produced.

316. ______________________________: Offspring must struggle to survive and reproduce.

317. ______________________________:

318. Offspring who inherited “fit” traits are, on average, better able to get resources, escape from predators and find mates.

319. Offspring with “unfit” traits will have more difficulty surviving and finding mates.

320. Fitness: A measure of how well a trait helps an organism to survive and reproduce in its environment. Note that there is no absolute rule for fitness – what is fit in one environment may be unfit in another.

321. Note: This “selection” is not a conscious act – no one is “choosing” who survives and who doesn’t. It is the result of the conditions of the organism’s environment.

322. ________________________________:

323. More fit organisms reproduce and pass on their genes than unfit organisms.

324. On average, the next generation will have more traits from the “fit” parents than the unfit ones.

325. NOTE: Traits are still inherited randomly. Individuals offspring of “fit” parents can still inherit “unfit” traits (though it will be unlikely to survive and reproduce). It is only by looking at the ENTIRE population that you will see the “fit” traits become more common.

326. _____________________: Evolution does not happen overnight. It takes many generations of repetitive selection to weed out the unfit traits.

327. Speciation: The process of making a new species from an existing one.

328. Geographic Isolation: A population is separated into 2 or more different habitats.

329. New variation and adaptation: Each population adapts to its new environment in different ways. This results in physical and genetic differences between the two populations.

330. Add time: The longer two populations are apart, the greater their differences will become.

331. Reproductive Isolation: Eventually the populations change so much that they are unable to interbreed, even when brought together.

332. Once two populations can no longer breed together, they are considered new species.

333. Classification- Organisms are classified based on their evolutionary relationship.

334. Kingdoms are large groups of related organisms (fungi, bacteria, protists, animals, plants).

335. A species is able to successfully reproduce amongst its members.

336. Note that this is not a perfect definition – Lions and tigers can breed together, as can dogs and wolves. Because evolution is a constantly ongoing and gradual process, there are many, many examples in which the lines between species are blurry (see Ring Species)

337. Branching tree diagrams (cladograms) are often used to show evolutionary relationships.

338. Evidence: Evidence in support of evolution comes from many fields:

339. Fossil record preserves extinct speices as well as transitional forms between different types of organisms.

340. Radiometric Dating of rocks consistently confirm the age of the Earth and fossils

341. Comparisons of the anatomy (physical structures), embryology (development), chemistry and genes of species confirm expected relationships.

342. Direct observation: Humans have seen evolution occur both in nature and in the lab. Examples include:

343. Bacteria evolving resistance to antibiotics.

344. Insects evolving resistance to pesticides.

345. Modeling natural selection with selective breeding to alter a species’ traits.

346. Observed examples of speciation

347. Common Mistakes

348. “Stronger organisms are more fit than weak ones.”

349. Evolutionary fitness is not physical fitness. Fitness is determined by who is better adapted to survive in a particular environment and who can pass on their genes. Stronger is not always better. There are many examples of species for whom it is better to be slow, weak, or stupid, than fast, strong or smart. It all depends on the environment you are in.

350. “The organism evolved to live in its environment.”

351. Individual organisms do not evolve. Only populations can evolve.

352. “The organism could not adapt and it went extinct.”

353. Individual organisms die; they cannot go extinct. Only species can become extinct.

354. “The bacteria became resistant to antibiotics when they were exposed to them”

355. To evolve, variations must exist in a species BEFORE the environment changes (pre-adaptation). Bacteria who did not already have a resistance to antibiotics would die when exposed to them, a Chihuahua who is left out in the cold will not grow long, warm fur and a squirrel who plays in traffic will not evolve automobile resistance.

356. “Giraffes got long necks because they needed them to eat leaves at the tops of trees.” Species do not evolve traits because they need them - Life would be much better if we could! Short necked giraffes were never given long necks any more than slower antelopes are given speed when confronted by a predator. The reason there are no short necked giraffes (or slow antelope) is that they were out competed by members of their species with more fit traits. Better answers are

357. “Giraffes evolved long necks because the ones with longer necks were better adapted to get food than short neck giraffes.”

359. Habitat: ____________________________________________

360. Niche: ______________________________________________

361. Two species in an ecosystem trying to fill the same niche will create________________________ , which usually results in only one species occupying a niche at any one time. Organisms with similar needs will often divide resources to reduce competition (ex: birds eat insects during the day, bats eat them at night).

362. How organisms interact with each other:

363. Competition: ____________________________________________________________

364. Ex: A squirrel and a chipmunk compete for food.

365. Feeding: One organism feeds on another.

366. Producer – An autotroph; organisms that makes its own nutrients from simple substances.

367. Consumer – A heterotroph; may be an herbivore, carnivore, omnivore or decomposer.

368. Symbiosis: A close relationship between two organisms in which at least one benefits.

369. Can include 2 organisms working together for mutual benefit (bee and flower) or 1 organism harming another (parasite-host).

370. Organization

371. Abiotic Factors: ________________________________________

372. Biotic Factors: _________________________________________

373. Levels of organization:

374. Populations: A given area can only supply enough resources for a limited number of organisms.

375. Carrying capacity: __________________________________________________

376. Limiting factors: Anything which limits the size of a population, including:

377. Overpopulation: When a population exceeds the carrying capacity. Usually results in a large number of organisms dying off until a new balance is reached.

378. 6064250117475Energy in an Ecosystem

379. _______________ provides all energy for life on Earth.

380. Sun’s energy is stored in the chemical _______________ of food through the process of ___________________________.

381. Food chain – Shows 1 way that energy can “flow” through an ecosystem.

382. Food web – Shows many energy pathways.

383. Energy pyramid: Shows that energy gets lost with each step in a food chain

384. Energy is lost because every organism uses some of the energy for it’s own life processes. Only about 10% of energy is passed from one step to the next.

385. This is why populations of predators are typically less than the populations of their prey.

386. 1479550140970

387. Biodiversity refers to the variety of life on earth.

388. Diverse ecosystems (those with many types of species) are more stable than ones that are not diverse.

389. As habitats are lost and species become extinct, biodiversity is reduced. This is considered to be bad because:

390. Ecosystems with low diversity are less stable than ecosystems with more diversity,

391. Ecosystems with low diversity take longer to recover from environmental changes

392. Humans use organisms for many things such as food and medicine; by reducing biodiversity we are losing potentially valuable resources.

393. Ecological Succession: ___________________________________________________________ ______________________________________________________________________________

394. The organisms in each stage of succession change the environment, and allow new organisms to move in and replace them.

395. Climax Community: __________________________________________________________

396. The climax community is determined by the local climate.

397. 2546350104775Ex: Kansas has very fertile soil, but not enough rain to support trees, so succession stops with grasses and shrubs.

398. Any temporary disruption of a community will begin the process of succession all over again.

399. Ex: If a forest fire kills all the trees in an area, succession will eventually return the area back into a forest, but it much first pass through all the necessary stages.

400. Human Impact: Human actions can have both a negative or positive impact on the environment.

401. The primary reason humans have a negative impact on the environment is because the human population is growing, which places a greater demand on resources such as food, water and space.

402. There are no easy solutions to any ecological problem. Every solution can have negative consequences. Choosing the “right” actions requires weighing the benefits with the risks.

403. Human actions that generally have a negative impact on the environment include:

404. Development/industrialization

405. Pollution

406. Farming

407. Overhunting,/overgrazing

408. Clear cutting/deforestation

409. Introduction of foreign species

410. Actions being taken by humans to reduce or repair damage to the environment include:

411. Recycling wastes

412. Conserving available resources

413. Using cleaner resources (ex: solar over fossil fuels)

414. Protection of habitats and endangered species

415. Use of biological controls instead of pesticides and herbicides

416. Farming native plants (ex: cocoa in the rainforest)

417. Planting trees to replace those cut down.

418. Rotating crops or planting cover crops to reduce soil loss.

419. Passing laws to control pollution, land management, hunting, fishing, etc.

420. Specific Environmental Problems:

421. Acid rain

422. Cause:

423. Negative effect:

424. What can be done:

425. Depletion of ozone layer

426. Cause:

427. Negative effect:

428. What can be done:

429. Industrialization

430. Cause:

431. Negative effect:

432. What can be done:

433. Loss of habitat (ex: deforestation)

434. Cause:

435. Negative effect:

436. What can be done:

437. Loss of diversity

438. Cause:

439. Negative effect:

440. What can be done:

441. Global warming

442. Cause:

443. Negative effect:

444. What can be done:

445. Introduced species

446. Cause:

447. Negative effect: