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Phloem is the second type of vascular tissue; it transports sugars, proteins, and other solutes throughout the plant. Phloem cells are divided into sieve elements (conducting cells) and cells that support the sieve elements. Together, xylem and phloem tissues form the vascular system of plants.

Roots: support for the plant

Roots are not well preserved in the fossil record. Nevertheless, it seems that roots appeared later in evolution than vascular tissue. The development of an extensive network of roots represented a significant new feature of vascular plants. Thin rhizoids attached bryophytes to the substrate, but these rather flimsy filaments did not provide a strong anchor for the plant; neither did they absorb substantial amounts of water and nutrients. In contrast, roots, with their prominent vascular tissue system, transfer water and minerals from the soil to the rest of the plant. The extensive network of roots that penetrates deep into the soil to reach sources of water also stabilizes trees by acting as a ballast or anchor. The majority of roots establish a symbiotic relationship with fungi, forming mycorrhizae, which benefit the plant by greatly increasing the surface area for absorption of water and soil minerals and nutrients.

Leaves, sporophylls, and strobili

A third innovation marks the seedless vascular plants. Accompanying the prominence of the sporophyte and the development of vascular tissue, the appearance of true leaves improved their photosynthetic efficiency. Leaves capture more sunlight with their increased surface area by employing more chloroplasts to trap light energy and convert it to chemical energy, which is then used to fix atmospheric carbon dioxide into carbohydrates. The carbohydrates are exported to the rest of the plant by the conductive cells of phloem tissue.

The existence of two types of morphology suggests that leaves evolved independently in several groups of plants. The first type of leaf is the microphyll    , or “little leaf,” which can be dated to 350 million years ago in the late Silurian. A microphyll is small and has a simple vascular system. A single unbranched vein    —a bundle of vascular tissue made of xylem and phloem—runs through the center of the leaf. Microphylls may have originated from the flattening of lateral branches, or from sporangia that lost their reproductive capabilities. Microphylls are present in the club mosses and probably preceded the development of megaphylls , or “big leaves”, which are larger leaves with a pattern of branching veins. Megaphylls most likely appeared independently several times during the course of evolution. Their complex networks of veins suggest that several branches may have combined into a flattened organ, with the gaps between the branches being filled with photosynthetic tissue.

In addition to photosynthesis, leaves play another role in the life of the plants. Pine cones, mature fronds of ferns, and flowers are all sporophylls —leaves that were modified structurally to bear sporangia. Strobili are cone-like structures that contain sporangia. They are prominent in conifers and are commonly known as pine cones.

Questions & Answers

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Mary
Meiosis is a biological processes that involves the division of sex cells
Musoke
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carbon the forth
Elsabet
Carbon fourth
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Biology is the study of living organism and their interaction with one another and their environment
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where are pollen grains produced pls.
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And what are emphatic factors.
Chinyi
@Chinyi Bahiyah -pollen grains are produced in the anther of plants. the anther is one part of the male part of the plant the other being filament and they together form the stamen. hoped that helped :) !!
xjuicy_editzz
biosphere is the regions surface and atmosphere of the earth (or other planets) where living organism's exist.
Esnart
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Science is the method of acquiring skills and knowledge through experimentation and observation in the World Series
Richmond
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Bitwell
is the study that deals with the interaction between living things and their environment
Alexander
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Liteboho
the main function is to uptake of water and nutrients from the rhizosphere.
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Jaymez
Science is the study of living things and non living thing
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plant cell is plasmolysed as a result of the
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is the study of cell and structure of an organism
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the study of living things
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because they are capable of reaching speeds of up to 70mph
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Diffusion is the movement of molecules from high concentration to low concentration
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Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
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