1. Relate Cause and Effect Describe how selective breeding was used to develop corn from an ancestral grass that looked very different

2. Infer What effect could plant species extinction have on therapeutic drug development

CH 24 PLANT REPRODUCTION AND RESPONSE24.4 Plants and Humans

Most people worldwide depend on four crop plants for the bulk of their food supply Rice Wheat Soybeans Corn.

Beginning of human civilization linked to the cultivation of crop plants

Planting and harvesting of crops tended to keep people in one place for much of the year Lead directly to the establishment of social institutions.

Most of our food comes from seeds of plants Roughly 80% of all U.S. cropland is used to grow

just four crops: wheat, corn, soybeans, and hay Three of them are grasses.

Efficiency of agriculture has been improved through the selective breeding of crop plants and improvements in farming techniques.

Corn grown by Native Americans was developed more than 8000 years ago from teosinte, a wild grass found in Mexico.

Changes caused by selective breeding has greatly exaggerated modern corn kernels compared to its ancestor, teosinte.

Plants as different as cabbage, broccoli, and brussel sprouts have been developed from a single species of wild mustard

Sugar beets came from selectively breeding the ordinary garden beet.

Improvements in farming techniques have contributed to dramatic improvements in crop yields Use of fertilizers and pesticides Labeled with three numbers that reflect the

percentage by weight of three elements: nitrogen (N), phosphorus (P), and potassium (K).

Overfertilizing can kill crop plants by putting too high a concentration of salts into the soil

Fertilizer runoff from the fields may contaminate streams, wetlands, lakes, and groundwater

Chemical pesticides can harm wildlife and leave dangerous chemical residues in food.

How is food grown/raised in the US What does that require

Non mechanized farming can yield 10-20 kcals per kcal spent to grow food

US gets back only .1 kcal per 1 kcal spent Overall loss of energy NOTE: We grow incredibly higher total amounts of

food with mechanized farming.

Plants produce the raw materials for our homes and clothes, and some of our most powerful and effective medicines Aloe vera contains many chemicals that soothe and

moisturize the skin Spruce wood is ideal for use in musical instruments Cotton is used in many products including thread,

bandages, carpet, and insulation.

By about how much did the amount of corn produced per acre of farmland increase between 1985 and 2005?

How would you describe the overall trend in the data?

Predict What factors do you think might influence corn production in the next decade?