This includes all animals apart from the subphylum Vertebrata. Familiar examples of invertebrates include insects; crabs, lobsters and their kin; snails, clams, octopuses and their kin; starfish, sea-urchins and their kin; and worms. The majority of animal species are invertebrates; one estimate puts the figure at 97%.
Answer:
Answer B. Endosymbiosis
Explanation:
Early protists were first eukaryotic organisms and had several membrane bound organelles. The anaerobic protists evolved by acquiring purple bacteria. The purple bacteria have the ability to carry out aerobic cellular respiration. The endosymbiont transformed into mitochondria in due course of evolution. Similarly, the photosynthesizing protists were evolved by endosymbiosis of cyanobacteria which in turn was transformed into chloroplast during further evolution.
Answer:
The correct selection of answers to the question: Identify the pieces of evidence describing the features of DNA that Watson and Crick used to determine the structure of DNA, would be:
C: The two chains are parallel, both running in a 5´ to 3´ direction
D: A purine base forms hydrogen bonds to pair with a pyrimidine base located on the opposite DNA strand. Specifically, A pairs with T, and C pairs with G.
E: The sugar-phosphate backbones of each DNA helix run antiparallel to one another
F: The diameter of the DNA doube helix is 2 nm, with each purine-pyrimidine base pair spanning an equivalent distance between the two chains.
Explanation:
Although Watson´s and Crick´s research, and model of the DNA helix, became the breakthrough for science, as it visually presented the now known characteristics of DNA, this research was possible due to the way that these two researchers used previous information found by other scientist on the molecule, to finally build their model. All of the options that were selected were part of the research of several scientis, including Mendel, Rosalin Franklin, Linus Pauling, Maurice Wilkins, Oswald Avery and many others, who worked on different aspects of specimens and their specific characteristics, and which led them to discover that organisms possessed DNA, that this was the unit of information that directed all functions in living cells and how this DNA helix was chemically built to understand how it worked, and why it worked the way it did.
