Cross section (geometry) of Earth at right. Cross-sections are often used in anatomy to illustrate the inner structure of an organ, as shown at left. A cross-section of a tree trunk, as shown at left, reveals growth rings that can be used to find the age of the tree and the temporal properties of its environment. Cross section (geometry) In geometry and science, a cross section is the non-empty intersection of a solid body in three-dimensional space with a plane, or the analog in higher-dimensional spaces. Cutting an object into slices creates many parallel cross sections. The boundary of a cross section in
Horizontal resistance Horizontal resistance In genetics, the term horizontal resistance was first used by J.E. Vanderplank to describe many-gene resistance, which is sometimes also called generalized resistance. This contrasts with the term vertical resistance which was used to describe single-gene resistance. Raoul A. Robinson further refined the definition of horizontal resistance. Unlike vertical resistance and parasitic ability, horizontal resistance and horizontal parasitic ability are entirely independent of each other in genetic terms. In the first round of breeding for horizontal resistance, plants are exposed to pathogens and selected for partial resistance. Those with no resistance die, and plants unaffected by the pathogen