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Keadaan Bumi Kita.......

   Pemanasan global mengancam kedaulatan negara. Es yang meleleh di kutub-kutub mengalir ke lautlepas danmenyebabkan permukaan bumi–termasuk lautlaut diseputar Indonesia–terus meningkat. Pulau-pulau kecilterluar kita bisa lenyapdari peta bumi, sehingga gariskedaulatan negarabisa menyusut. Diperkirakan dalam 30 tahunmendatangsekitar 2.000 pulau di Indonesia akantenggelam. Bukanhanya itu, jutaan orang yang tinggal di pesisir pulaukecil pun akan kehilangan tempat tinggal. Begitupulaaset-aset usaha wisata pantai.     Pemanasan global adalah kejadian terperangkapnya radiasi gelombang panjangmatahari (disebut juga gelombang panas/inframerah) yang dipancarkan bumi olehrumah kaca (efek rumah kaca adalah istilah untuk panas yang terperangkapdi dalam atmosfer bumi dan tidak bisa menyebar). Gas-gas ini secara alamiterdapat di udara (atmosfer). Penipisan lapisan ozon juga memperpanas suhu bumi. Karena, makin tipis lapisan lapisan teratas atmosfer, makin leluasa radiasigelombang pendek matahari (termasuk ultraviolet) memasuki bumi. Padagilirannya, radiasi gelombang pendek ini juga berubah menjadi gelombang panas, sehingga kian meningkatkan konsentrasi gas rumah kaca tadi. gas-gas

     Karbondioksida (CO2) adalah gas terbanyak (75%) penyumbang emisi gas rumah kaca. Setiap kali kita menggunakan bahan bakar fosil (minyak, bensin, gas alam, batubara) untuk keperluan rumah tangga, mobil, pabrik, ataupun membakarhutan, otomatis kita melepaskan CO2 ke udara. Gas lain yang juga masuk peringkatatas adalah metan (CH4,18%), ozone (O3,12%), dan clorofluorocarbonmetan banyak dihasilkan dari proses pembusukan materi organic seperti yang banyak terjadi di peternakan sapi. Gas metan juga dihasilkan daripenggunaan BBM untuk kendaraan. Sementara itu, emisi gas CFC banyak timbuldari sistem kerja kulkas dan AC model lama. Bersama gas-gas lain, uap air ikut (CFC,14%). Gas meningkatkan suhu rumah kaca.

.::Gloria Cyber Ministries::

.::Gloria Cyber Ministries::

Manfaat Petai |Pengobatan Penyakit & Alternatif : Tanaman Obat - Konsultasi Kesehatan & Penyakit Jantung| Knowledge | 88DB Indonesia

Manfaat Petai |Pengobatan Penyakit & Alternatif : Tanaman Obat - Konsultasi Kesehatan & Penyakit Jantung| Knowledge | 88DB Indonesia

Membran Transport sysTem

Membrane transport systems

          One function of the cell membrane is as molecules and ions traffic in both directions.

Molecules that can pass through cell membranes, among others, are hydrophobic molecules (CO2, O2), and a very small polar molecules (water, ethanol). Meanwhile, other molecules such as polar molecules with large size (glucose), ions and hydrophilic substances require special mechanisms for entry into the cell.

                                                                    

A. Passive transport

         Passive transport is movement of molecules down a concentration gradient. This passive transport spontaneous.

Diffusion, osmosis, facilitated diffusion and is an example of passive transport.

Diffusion occurs due to thermal motion which increases the entropy or disorder resulting in a more andom mix. Diffusion will continue for respiration, which consumes O 2 entry. Osmosis is the diffusion of solvent across the membrane selective displacement direction is determined by the total solute concentration difference (from hipotonis to hipertonis). Facilitated diffusion is also still considered to be due to the passive transport of solutes move according to their concentration gradients.

    Osmosis

Is the movement of water through a selectively permeable membrane from the more dilute to the more dense. Semipermeable membrane must be penetrated by solvent, but not by the solute, which causes the pressure gradient along the membrane. Osmosis is a natural phenomenon, but can be inhibited artificially by increasing the pressure on the parts with dense concentration exceeds its concentration becomes more dilute. Force per unit area required to prevent the flow of solvent through a selectively permeable membrane and enter the solution with a more intense concentration is proportional to the turgor pressure.

If a plant cell is placed in concentrated salt solution (hypertonic), plant cells lose water and turgor pressure, resulting in weak plant cells. Plants with cells in this condition wilt. Lose more water will cause plasmolysis: keep the pressure decreases until at a point where the protoplasm of cells scraped from the cell wall, causing the distance between cell walls and membranes. Finally cytorrhysis - the collapse of the entire cell wall - can occur. There is no mechanism in plant cells to prevent excessive water loss, also get water in excess, but plasmolysis can be reversed if the cell is placed in hypotonic solution.

Crenation

Crenation is the contraction or formation of abnormal nokta around the edges of the cells after inserted into the hypertonic solution

Crenation occurs because hypertonic environment, (the cell has a solution with a lower concentration than the solution around the outside of cells), osmosis (diffusion of water) causing movement of water out of cells, causing reduced cytoplasmic volume. As a result, the cells shrink.
Same process that occurs in plants is a plant cell plasmolysis which is also shrinking due to put in a hypertonic solution

B. Active transport

            Is the opposite of passive transport and is not spontaneous. The direction of this transport movement against a concentration gradient. Active transport requires the help of several proteins. Examples of proteins involved in active transport is the channel proteins and carrier proteins, as well as ionophore

           Active transport is divided into primary and secondary active transport. Secondary active transport is also composed of co-transport and counter transport (exchange).
Primary active transport directly uses energy from ATP, such as the Na-K pump and Ca pump. In the Na-K pump, 3 Na is pumped out of the cell was 2 K will be pumped into the cell. In the Ca pump, ca will be pumped out of cells to low concentrations of Ca in the cell.

                                                                     

The diffferent Between Animal cell and Plant Cell

The Different Between Animal Cell and Plant Cell