As eggs develop, the volume of yolk decreases relative to the volume of the embryo. Why do you ...

Student answers will vary but should include references to the yolk being absorbed
as the chick grows.

Using insecticides with cautionary measures (students should not use this method
unless under close adult supervision and with complete knowledge of the
insecticides' dangers and effects), introducing natural predators of the insects,
destroying insects manually.

Student answers may vary and the students should be able to identify the insects as
harmful because of physical evidence such as (1) defoliation, (2) deformation of
stems, (3) girdling, (4) discoloration of leaves, (5) wilting, and (6) leaf loss.

Student answers may vary due to the types of insects present and the degree of
insect defoliation.

Student answers may vary due to (1) growth characteristics of different plants, (2)
differences in soil qualities of each garden, and (3) climatic and environmental
factors.

Students should describe the degree and type of growth observed in the different
plots.

Your students need to have information about the two forest areas such as the
length of time since the last tree harvest, the numbers of trees that were cut, and
whether the area was left to naturally recover or whether it was replanted.
Encourage your students to think about the kinds of trees that are found in
undisturbed forest habitats in your area.

All forests are a product of ecological succession. A fallow field will quickly become
populated with grasses and small shrubs. The shrubs will be replaced by small trees
in time. Over many years, the types of trees that grow in an area that has been
undisturbed for at least 50 to 100 years is characteristic of biome for the area. For
example, in the southeastern United States, the climax forest vegetation is an oak,
hickory, and chestnut forest. In higher elevations of the western Rocky Mountains,
the climax vegetation is a coniferous forest. Biomes are vegetation belts produced by
the temperature and rainfall patterns common to the area. The age of the forest
would determine which vegetation in the successional patterns for your biome
would be found in the forest area. Available water is an important consideration.
Some tree species have high water requirements and will only grow in saturated
soils, such as bald cypress and Tupelo. Other trees, like willows and water oaks,
grow in forest sites with large amounts of water, such as locations on the banks of
rivers, streams, and lakes.