Â©2003 Why is there a decision to make about having mammograms to screen for breast cancer? A mammogram every two years to screen for breast cancer reduces the chance of dying from breast cancer among women aged 50 to 69 years. It is unclear if women aged 70 years and older get the same benefits. mammogram every two years to screen for breast cancer reduces the chance of dying from breast cancer among women aged 50 to 69 years. It is unclear if women aged 70 years and older get the same benefits.
Temperate grasslands are located north of the Tropic of Cancer (23.5 degrees North) and south of the Tropic of Capricorn (23.5 degrees South). The major temperate grasslands include the veldts of Africa, the pampas of South America, the steppes of Eurasia, and the plains of North America.
Temperate grassland. Temperate grasslands are characterized as having grasses as the dominant vegetation. Trees and large shrubs are absent. Temperatures vary more from summer to winter, and the amount of rainfall is less in temperate grasslands than in savannas.avanna. Savanna is grassland with scattered individual trees. Savannas of one sort or another cover almost half the surface of Africa (about five million square miles, generally central Africa) and large areas of Australia, South America, and India. Climate is the most important factor in creating a savanna.