Answer:
Sonic Hedgehog.
Explanation:
Sonic hedgehog is a secreted protein that in humans is encoded by the SHH gene. It is the best studied ligand of the hedgehog signaling pathway, others being desert hedgehog (DHH) and Indian hedgehog (IHH). It plays a key role in the development of animals, from insects to mammals. In vertebrates, it is involved in organogenesis, including the growth of digits on limbs and the organization of the brain.
Sonic hedgehog has also been shown to act as an axonal guidance cue. It has been demonstrated that SHH attracts commissural axons at the ventral midline of the developing spinal cord. Specifically, SHH attracts retinal ganglion cell (RGC) axons at low concentrations and repels them at higher concentrations
Answer: The tracheids have important functions in the plant.
Explanation: The mechanical support is provided by the lignified walls of tracheid cell. the helps in other functions of the plant such as transporting water and getting the solute from the root to the stem and eventually the leaf of the plant.
The tracheids are most useful in the gymnosperms where elements need to be transported.
Identifying a tracheid in a cross section is quire easy as the tracheid cells fit into each other neatly and piled up similarly and have identical shapes as well which makes them obvious from other cells.
The two examples of tracheid plans could be
The most common thing that could be found in traceid plant is that this cells are mainly present for transporting either water other solutes in the plant body.
Answer:
The plant cell wall is strengthened by the molecular structure of cellulose. Cellulose is made up of ß-glucose arranged upside down, this arrangement aided hydrogen bonds between the hydrogen ions of the hydroxyl group and oxygen of the of the ring of same betta -glucose.
The aggregation of the hydrogen bonds give bundles of strong tensile strength of cellulose called the microfibrils (of 60-70 celluose molecules).They are held together in bundled called fibers.T<u>hese is the source of plant cell walls strength.
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Collagen is the main extracellur matrix (EM) in animal cells.It is a glycoprotein made up of 25%of body protein of animals.Each collagen molecule is made of helix shaped ,three polypeptide chains, wound around each other to form<u> triple helix.</u>The bonds holding helix together are hydrogen and covalent bonds.
Each triple helix is attached to adjacent collagen molecule, parallel to it. The covalent bonds formed a cross link which held the collagen molecules together forming FIBRILS. This gives flexibility to collagen, while maitaing strong tensile strength. This is what is responsible for the structural strength of cell membrane
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.The EM,is futher reinforced with carbohydrate molecules(proteoglycans) which<u> aided in water movements by osmosis following sodium movements into the matrix.</u>
Answer:
Mangrove forest
Explanation:
Mangrove forest exist only in high saline environment. Lake is a closed type body of water so it is expected with the least variation of salinity.
Geocentric - Earth Centered solar system
Heliocentric - Sun Centered solar system
