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Knowledge and Skills Statement

Science concepts--biological structures, functions, and processes. The student knows that multicellular organisms are composed of multiple system that interact to perform complex function.

Examples of asexual reproduction:

  • Budding occurs when a complete offspring grows from the parent plant at a particular spot such as when multiple new potato plants grow from the eyes of a single potato.
  • Fragmentation occurs when a new plant grows from a small portion of the parent that broke off and rooted in the ground. This occurs most often in mosses.
  • Vegetative propagation occurs when new plants are generated from the vegetative components of the parent plant, such as runners, rhizomes, or tubers.
  • Spore formation occurs in ferns. Ferns alternate generations between asexual haploid plants and sexual diploid plants.


Sexual reproduction in plants occurs through multiple different mechanisms, including flowering plants (angiosperms) and conifers (gymnosperms).
 

Tropisms are directional growth responses of plant organs to environmental stimuli. Positive tropisms occur when the plant grows toward the stimulus and negative tropisms cause a plant to grow away from the stimulus. Different parts of the plant may respond positively or negatively to the same stimulus. For example, stems are negatively gravitropic and roots are positively gravitropic. One hormone that has been shown to participate in gravitropism and phototropism is auxin. Auxin accumulates within parts of the plant and stimulates elongation. The signals responsible for hydrotropism and thigmotropism have yet to be determined.

Another way in which plants respond to the environment is dormancy. Some plants go dormant in the winter to survive cooler temperatures and drier weather.

Plants also respond to illness. If a plant becomes infected, it will often kill the cells surrounding the diseased tissue so the infection does not spread. A plant can also produce hormones or toxins like salicylic acid to fight pathogens.

the reason for which an object or a process occurs in a system

something arranged in a definite pattern of organization; the arrangement of particles or parts in a substance or body; the aggregate of elements of an entity in their relationships to each other

regularly interacting or interdependent group of items forming a unified whole

Research

Cornelis, Salves and Ora Hazak. "Understanding the Root Xylem Plasticity for Designing Resilient Crops." Plant Cell Environment 45, no.3 (March 2022): 664-676. doi: 10.1111/pce.14245.

Summary In this review, we summarize recent findings on the molecular mechanisms of xylem formation that largely come from Arabidopsis research with additional insights from tomato and monocot species. We emphasize the impact of abiotic factors and pathogens on xylem plasticity and the urgent need to uncover the underlying mechanisms. Finally, we discuss the multidisciplinary approach to model xylem capacities in crops.