Answer: Ultimately, a beach erodes because the supply of sand to the beach can not keep up with the loss of sand to the sea. Most sand is transported from inland via rivers and streams. The damming of most waterways in the US has thus prevented a major supply of sand from getting to our beaches.
Answer:
smooth endoplasmic reticulum
Explanation:
Smooth endoplasmic reticulum differs from the rough endoplasmic reticulum in not having ribosomes on its surface. The smooth endoplasmic reticulum (SER) extends from the rough ER and forms a network of membrane tubules. The function of the smooth ER is to serve as a site for the synthesis of lipids, fatty acids, and steroids such as estrogens and testosterone.
Enzymes for the synthesis of these diverse biomolecules are present in smooth ER. The smooth ER present in the muscle cells is called the sarcoplasmic reticulum. It stores the calcium ions which are released into the sarcoplasm of muscle cells during muscle contraction.
Answer:
Pteridophytes are vascular plants but they do not produce flowers and seeds which mean their source of reproduction is unknown or hidden.
On the contrary, Spermatophytes as the name indicates, are seed bearing plants. They produced seeds and flowers. Examples are flowering plants, cactus, leather flower, buttercup and may more.
Explanation:
Answer:
sieve-tube elements, companion cells
Explanation:
Sieve-tube elements and companion cells are responsible for the movement of photosynthes through a plant.
The sieve tube elements are shorter (almost organelle-free) living cells, placed end to end, forming the sieve tubes. Their transverse cell walls are called sieve plaques that make connections between cells and through openings called sieves establish the connection between the cytoplasm of adjacent cells. Each sieve is coated with calose (glucose polymer), which in winter can completely clog the vessel and then dissolve in spring. When infections occur or the vessel is parasitized, it can also be clogged with callose.
Companion cells are specialized parenchymal cells, which contain all the components that exist in living cells, including the nucleus, are the cells most closely linked to the sieved tube element. The Screened Tube Element and its companion cells are related in development, are derived from the same mother cell, and have several cytoplasmic connections to each other. Due to the many connections, the potential function of the companion cells is to release substances into the sieved tube element and, when the nucleus is absent, to include information molecules, proteins and ATP. When a screened element dies, its companion cells also die, which is a demonstration of this interdependence.
