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T cells are one of the important types of white blood cells of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell receptor (TCR) on their cell surface. T cells are born from hematopoietic stem cells, [1] found in the bone marrow.
The T helper cells (T h cells), also known as CD4 + cells or CD4-positive cells, are a type of T cell that play an important role in the adaptive immune system. They aid the activity of other immune cells by releasing cytokines .
A nineteenth-century illustration showing the morphology of the roots, stems, leaves and flowers of the rice plant Oryza sativa. Plant anatomy is the study of the structure of plant cells and tissues, whereas plant morphology is the study of their external form. [181] All plants are multicellular eukaryotes, their DNA stored in nuclei.
Economic botany is the study of the relationship between people (individuals and cultures) and plants.Economic botany intersects many fields including established disciplines such as agronomy, anthropology, archaeology, chemistry, economics, ethnobotany, ethnology, forestry, genetic resources, geography, geology, horticulture, medicine, microbiology, nutrition, pharmacognosy, and pharmacology. [1]
Plant cells also contain chlorophyll, a chemical compound that interacts with light in a way that enables plants to manufacture their own nutrients rather than consuming other living things as animals do. Thirdly, plant physiology deals with interactions between cells, tissues, and organs within a plant. Different cells and tissues are ...
In addition to growth by cell division, a plant may grow through cell elongation. This occurs when individual cells or groups of cells grow longer. Not all plant cells grow to the same length. When cells on one side of a stem grow longer and faster than cells on the other side, the stem bends to the side of the slower growing cells as a result.
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Flowers and plants may be indoors in a sunny window, as part of the landscape in the front yard or on the patio or deck in the back yard. People have been studying flowers and plants and their interaction with humans and how to produce these flowers and plants so all humans can enjoy them. Floriculture scientists throughout the world to do this ...