biologia tema 3

DNA. Chemical composition: deoxyribonucleotides – phosphate, deoxyribose and nitrogenous bases A-T  G-C. Molecular structure: double-stranded structure. Types: Nuclear DNA that forms chromatin, Mitochondrial DNA found in mitochondria and Plastid DNA found in cloroplasts. Cell location: In the nucleus, mitochondria and clororplasts. Function: Contains the organism’s genetic information. RNA. Chemical composition: ribonucleotides - phosphate, ribose, nitrogenous bases A-U  G-C. Molecular structure:

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Arthropods (joint foot)

Form and Function: EXOSKELETON-  insects: flexible ticks & lobsters: hard

Many terrestrial have H2o proof exoskeleton, making it possible to live in extremely dry places. 

Jointed Appendages; enable movement. Examples: claws, antennae, legs, wings, flippers, etc.

Segmented bodies: Most have 3 segments. Centipede and millipede have more. Some have 2, because head and thorax= cephalothorax.

Respiration: crustaceans: gills, chelicerates: book gills and book lungs, insects:

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air masses


  • Warm air expands (density decreases) and rises up leaving an area of low pressure.
  • When air goes up through upper layers of the atmosphere cools down (se enfria). 
  • Cold air contracts going down into the atmosphere, generating a high-pressure area.
  • From high pressure area, air flows near Earth’s surface to low pressures, warming up. 
  • The circuit which air flows continuously: convective cell.
  • If Earth were motionless, air circulation would follow convective cells that would extend
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1.Ecosystems and environmental factors.Ecosystem:is a system formed by a group of organisms of different species(or biocenosis),the environment in which they live and its physical/chemical characteristics(or biotope) and the interactions.Types of environmental factors.Abiotic factor:are the physical/chemical components of an ecosystem(temperature,light,water).Biotic factors:interactions produced in the biocenosis(wolves when they hunt as a pack).Tolerance ranges and limiting factors:an environmental

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1.What is shigellosis? What bacteria cause shigellosis? How is infection acquired? How is infection treated? Shigellosis is a public health threat in developed as well as developing countries, it is an infectious disease caused by a group of bacteria called Shigella. The genus Shigella having four pathogenic serogroups (Shigella dysenteriae, Shigella flexneri, Shigella sonnei, and Shigella boydii). Shigellosis causes diarrhea, fever, and stomach cramps. One can contract Shigellosis by putting something
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Bio 201 Exam 2

DNA Structure: Phos Group gives DNA acid props. | DNA written 5′ to 3′ | Comp pairing pu-py so constant width, A(pu)-T(py) 2 H-bonds, G(pu)-C(py) 3 H-bonds | Backbone antiparallel, sugars upside down for pairing to occur, helix shields hydrophobic bases, 10 B.P. for rotation | Packages 3 bil B.P., 2 meters | Chromosomes 23 pairs, same genes differ in inherited sequence (diff. traits), condensed chromatin fiber loops | Histones allow wrapping of DNA, +Lysine/Argininebind with negative backbone

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