Chain reaction
17.36
Because a neutron is needed to instigate a fission (splitting) and neutrons are produced as the product of a fission, these products can go on to produce more fissions. The neutrons produced from these can then go on to produce more fissions etc.etc. Each stage is therefore linked to the previous one and therefore...
The atmosphere
04.27
The Earth's atmosphere is a layer of gases surrounding the planet Earth that is held in place by the pull of Earth's gravity. The Earth's atmosphere contains a mixture of gases is commonly known as air: 78% nitrogen, 21% oxygen, 0.93% argon, 0.04% carbon dioxide - although this is increasing water vapour (average...
The Endoplasmic Reticulum
22.01
The endoplasmic reticulum is an extensive network of membranes composed of both regions with ribosomes and regions without ribosomes.Endoplasmic ReticulumWhat are their distinguishing characteristics? There are two regions of the ER that differ in both structure and function. One region is called rough ER because it has ribosomes attached to the...
ribosome
21.23
Ribosomes are organelles that consist of RNA an proteins. They are responsible for assembling the proteins of the cell. Depending on the protein production level of a particular cell, ribosomes may number in the millions.Distinguishing Characteristics: Ribosomes are typically composed of two subunits: a large subunit and a small subunit. Ribosomal...
Mitochondria
21.11
Mitochondria are the cell's power producers. They convert energy into forms that are usable by the cell. They are the sites of cellular respiration which ultimately generates fuel for the cell's activities. What are their distinguishing characteristics? Mitochondria are bounded by a double membrane. Each of these membranes...
The Nucleus
21.03
The nucleus is a membrane bound structure that contains the cell's hereditary information and controls the cell's growth and reproduction. It is commonly the most prominent organelle in the cell.Distinguishing Characteristics: The nucleus is bounded by a double membrane called the nuclear envelope. This membrane separates the contents of the nucleus...
cilia and flagella
21.00
In Journey into the Cell, we looked at the structure of the two major types of cells: prokaryotic and eukaryotic cells. Now we turn our attention to the "movers" of a eukaryotic cell, cilia and flagella. What are cilia and flagella? Cilia and flagella are protrusions from some cells that aid in cellular locomotion. They are formed from specialized...
The Cell-Cell Structure
20.53
Life is both wonderful and majestic. Yet for all of its majesty, all organisms are composed of the fundamental unit of life, the cell. The cell is the simplest unit of matter that is alive. From the unicellular bacteria to multicellular animals, the cell is one of the basic organizational principles of biology. Let's look at some of the components...
Osmosis
09.25
Osmosis is a special case of passive transport. In osmosis water diffuses from a hypotonic (low solute concentrated) solution to a hypertonic (high solute concentrated) solution. Generally speaking, the direction of water flow is determined by the solute concentration and not by the "nature" of the solute molecules themselves. If the blood cells in...
Facilitated Diffusion
09.18
Facilitated diffusion is a type of passive transport that allows substances to cross membranes with the assistance of special transport proteins. Some molecules and ions such as glucose, sodium ions and chloride ions are unable to pass through the lipid bilayer of cell membranes.Through the use of ion channel proteins and carrier proteins that are...
Diffusion and Passive Transport
08.29
Diffusion Diffusion is the tendency of molecules to spread into an available space. This tendency is a result of the intrinsic thermal energy (heat) found in all molecules at temperatures above absolute zero. Without other outside forces at work, substances will move/diffuse from a more concentrated environment to a less concentrated environment. No...
Animal Cells
07.52
Animal cells are eukaryotic cells, or cells with a membrane-bound nucleus. Unlike prokaryotic cells, DNA in animal cells is housed within the nucleus. In addition to having a nucleus, animal cells also contain other membrane-bound organelles, or tiny cellular structures, that carry out specific functions necessary for normal cellular operation. Organelles...
Anatomy of the Heart: Aorta
17.56
What is the aorta? The aorta is the largest artery in the body. Arteries are vessels that carry blood away from the heart. The aorta arises from the left ventricle of the heart, forms an arch, then extends down to the abdomen, where it branches off into two smaller arteries. Function of the Aorta The aorta carries and distributes oxygen rich blood...
Capillary
08.55
What Is a Capillary? A capillary is an extremely small blood vessel located within the tissues of the body, that transports blood from arteries to veins. Capillaries are most abundant in tissues and organs that are metabolically active. For example, muscle tissues and the kidneys have a greater amount of capillary networks than do connective tissues....
Ventricles of the Heart
08.53
Ventricles of the Heart The heart is divided into four chambers that are connected by heart valves. The lower two chambers of the heart are called ventricles. They are separated by a septum into the left ventricle and the right ventricle. The upper two heart chambers are called atria. Atria receive blood returning to the heart from the body and ventricles...
Vein
08.47
A vein is an elastic blood vessel that transports blood from various regions of the body to the heart. Veins can be categorized into four main types: pulmonary, systemic, superficial, and deep veins.Pulmonary veins carry oxygenated blood from the lungs to the left atrium of the heart. Systemic veins return deoxygenated blood from the rest of the body...
Artery
08.34
An artery is an elastic blood vessel that transports blood away from the heart. There are two main types of arteries: pulmonary arteries and systemic arteries.Pulmonary arteries carry blood from the heart to the lungs where the blood picks up oxygen. The oxygen rich blood is then returned to the heart via the pulmonary veins. Systemic arteries deliver...
Microcirculation
05.19
Microcirculation deals with the circulation of blood from the heart to arterioles (small arteries), to capillaries, to venules (small veins) and back to the heart. The liver, spleen and bone marrow contain vessel structures called sinusoids instead of capillaries. In these structures, blood flows from arterioles to sinusoids to venules. A vessel called...
CERN on trial: could a lawsuit shut the LHC down?
05.16
COURTS and legal scholars love quoting legal maxims in Latin. One of the most famous is fiat justitia ruat caelum. The phrase is a resolute affirmation of the rule of law. It means "Let justice be done though the heavens fall". It was intended as hyperbole. But,...
Mathematicians offer tip-offs to LAPD
05.14
Los Angeles police are getting tip-offs from unlikely informants: mathematicians. Using crime data from southern California, Jeffrey Brantingham of the University of California, Los Angeles, and his colleagues set out to calculate how the movements of criminals...
World's most sensitive neutrino experiment begins
05.10
An intrepid subatomic particle has travelled through the bedrock of Japan and triggered a detector on the other side of the country, heralding a new attempt to probe the mystery of neutrino oscillations. The result could take us closer to answering one very big question – why is the universe full of matter? ...
Awas, Vila di Puncak Akan Dipangkas
04.49
Menteri Negara Lingkungan Hidup Gusti Muhammad Hatta menargetkan dapat menurunkan jumlah vila yang berada di kawasan puncak, Bogor, Jawa Barat."Kita harapkan setiap tahun ada penurunan jumlah vila," kata MenLH pada acara penanaman pohon di area Situ Cibeureum, Bojong Gede, Bogor, Jawa Barat, Jumat (8/1/2010).Dia...
Harimau Sumatera Akan Dilepaskan Lagi di Hutan Tambling
04.41
Pelepasliaran harimau sumatera (Panthera tigris sumatrae) akan kembali dilakukan di kawasan Tambling Wildlife Nature Conservation (TWNC). Hutan konservasi yang terletak di Lampung bagian timur ini merupakan salah satu bagian dari hutan alam yang masih asli."Kami berencana melakukan pelepasliaran harimau...
Matinya "Emi" Si Cula Dua
04.34
- Sungguh malang nasib Emi. Seekor badak Sumatera (Dicerorhinus sumatrensis) betina yang telah 14 tahun tinggal dan berkembang biak di Kebun Binatang Cincinnati, Ohio, Amerika Serikat itu mati pada 5 September 2009 di usia 21 tahun karena sakit. Kematian Emi juga menjadi duka bagi para ilmuwan dan orang-orang...
Rosa Lebih Tertarik dengan Manusia
04.31
BOGOR, Ada-ada saja ulah Rosa, seekor badak betina yang tinggal di penangkaran Suaka Rhino Sumatera (SRS) Way Kambas, Lampung, ini lebih tertarik dengan manusia ketimbang badak jantan."Kayak anjing peliharaan deh Mbak, mintanya diajak main. Dia emang deket banget sama manusia, beda sama yang lain. Pas kita di tenda, dia suka masuk ke tenda,"...
Macan Tutul Jawa Tertangkap Kamera TNGHS
04.30
Dua ekor macan tutul jawa (Panthera padus melas) dewasa tertangkap kamera yang dipasang tim pemantau macan Balai Taman Nasional Gunung Salak Halimun (TNGSH) belum lama ini. Hasil cetak foto dari kamera tersebut, juga mengungkap jalur jelajah satwa langka tersebut dilintasi oleh manusia. ...
Induknya Kabur, Anak Orangutan Dipelihara Universitas
04.28
Kesadaran masyarakat terhadap konservasi lingkungan masih tetap rendah. Vera, misalnya, bayi orangutan (Pongo pygmaeus) berumur dua tahun ini akan diselundupkan ke Arab Saudi, tetapi digagalkan Balai Karantina Bandar Udara Soekarno-Hatta, Tangerang, dan diserahkan kepada Departemen...
Tumbuhan Menjalar Ganggu Habitat Badak dan Hewan Liar Lainnya
04.28
Ada beberapa kendala dari luar yang menghambat perkembangbiakan badak Sumatra. Salah satunya adalah serangan tumbuhan menjalar mantangan (Meremia peltata) yang merambah habitat badak dengan cepat.Hal tersebut disampaikan Kepala Yayasan Badak Indonesia (YABI), Widodo Ramono usai jumpa pers di Hotel Santika,...
Ekosistem Bukit Soeharto Kian Terancam
04.26
Bukit Soeharto adalah kawasan yang menjadi hamparan hutan tropis basah dataran rendah yang pada Pemerintahan Orde Baru diharapkan jadi etalase kondisi hutan di Indonesia.Karena letaknya mudah dijangau, yakni berada pada poros Jalan Lintas Kalimantan di Kaltim yang menghubungkan Balikpapan-Samarinda.Penamaan...
Ekosistem Bukit Soeharto Kian Terancam
04.26
Bukit Soeharto adalah kawasan yang menjadi hamparan hutan tropis basah dataran rendah yang pada Pemerintahan Orde Baru diharapkan jadi etalase kondisi hutan di Indonesia.Karena letaknya mudah dijangau, yakni berada pada poros Jalan Lintas Kalimantan di Kaltim yang menghubungkan Balikpapan-Samarinda.Penamaan...
Danau Sentani Papua Septictank Besar Warga
04.25
Alam kebanggaan Papua, Danau Sentani di Jayapura perlahan namun pasti sedang menuju kerusakannya. Danau dengan pulau-pulau kecil di dalamnya ini terancam oleh sedimentasi/pendangkalan akibat aktivitas di Pegunungan Cagar Alam Cycloops, sampah rumah tangga, hingga sampah bahan beracun berbahaya."Danau Sentani ini juga sudah mirip dengan septictank besar,...
Sadis, Bunga Raflesia Ini Dipotong Satu Kelopaknya
04.23
Bunga Raflesia (Raflesia arnoldi) yang sedang mekar sempurna di Km 40 jalan lintas Kota Bengkulu-Kepahiang dirusak oknum tak bertanggungjawab dengan memotong salah satu kelopak bunganya.Anggota tim Peduli Puspa Langka Tebat Monok Kabupaten Kepahiang, Holidin mengatakan bunga tersebut mekar hanya berjarak...
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