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3 years ago

What do scientists use to mark boundaries in the geologic time scale?

Biology

1 answer:

tekilochka [14]3 years ago

3 0

Era is used to mark the boundaries of geological time scale by using radio carbon dating technique.

Explanation:

Geological time starts with Precambrian time.

Geologically, time is divided between the Precambrian era and present time into era.

The three eras are Paleozoic era, Triassic period and Cenozoic era.

Era is further divided into periods.

Scientists use radio carbon dating to study fossils and rock formation. With this study they were able to divide them in exact geological scale.

Geologic scale is the record of events in earth's history and evolution.

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A biologist has mixed the polysaccharide agarose with other components to create a gel.

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Number of different amino acids that make up all proteins

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List of the 20 Amino Acids

Amino Acid 3-Letter Abbreviation 1-Letter Abbreviation Class of Amino Acid (Side Chain) Hydrophobicity Index (100 being extremely hydrophobic, 0 being neutral, and -55 being hydrophilic) Structure pKa of COOH group pKa of NH3+ group pKa of R group Molecular Weight [g/mol] alpha helix beta sheet Reverse turn

Glycine Gly G Aliphatic, nonpolar Neutral (0 at pH = 2; 0 at pH = 7)

2.4 9.8 -- 75.07 0.43 0.58 1.77

Alanine Ala A Aliphatic, nonpolar Hydrophobic (47 at pH = 2; 41 at pH = 7)

2.4 9.9 -- 89.1 1.41 0.72 0.82

Valine Val V Aliphatic, nonpolar Very Hydrophobic (79 at pH = 2; 76 at pH = 7)

2.3 9.7 -- 117.15 0.90 1.87 0.41

Leucine Leu L Aliphatic, nonpolar Very Hydrophobic (100 at pH = 2; 97 at pH = 7)

2.3 9.7 -- 131.18 1.34 1.22 0.57

Isoleucine Ile I Aliphatic, nonpolar Very Hydrophobic (100 at pH = 2; 99 at pH = 7)

2.3 9.8 -- 131.18 1.09 1.67 0.47

Methionine Met M Hydroxyl or Sulfur-Containing, nonpolar Very Hydrophobic (74 at pH = 2; 74 at pH = 7)

2.1 9.3 -- 149.21 1.30 1.14 0.52

Serine Ser S Hydroxyl or Sulfur-Containing, polar Neutral (-7 at pH = 2; -5 at pH = 7)

2.2 9.2 -- 105.09 0.57 0.96 1.22

Cysteine Cys C Hydroxyl or Sulfur-Containing, polar Hydrophobic (52 at pH = 2; 49 at pH = 7)

1.9 10.7 8.4 121.16 0.66 2.40 0.54

Threonine Thr T Hydroxyl or Sulfur-Containing, polar Neutral (13 at pH = 2; 13 at pH = 7)

2.1 9.1 -- 119.12 0.76 1.17 0.96

Proline Pro P Cyclic Hydrophilic (-46 at pH = 2; -46 at pH = 7)

2.0 9.6 -- 115.13 0.34 0.31 1.32

Phenylalanine Phe F Aromatic Very Hydrophobic (92 at pH = 2; 100 at pH = 7)

2.2 9.3 -- 165.19 1.16 1.33 0.59

Tyrosine Tyr Y Aromatic Hydrophobic (49 at pH = 2; 63 at pH = 7)

2.2 9.2 10.5 181.19 0.74 1.45 0.76

Tryptophan Trp W Aromatic Very Hydrophobic (84 at pH = 2; 97 at pH = 7)

2.5 9.4 -- 204.25 1.02 1.35 0.65

Histidine His H Basic Hydrophilic at pH=2 (-42), Neutral at pH=7 (8)

1.8 9.3 6.0 155.16 1.05 0.80 0.81

Lysine Lys K Basic Hydrophilic (-37 at pH = 2; -23 at pH = 7)

2.2 9.1 10.5 146.188 1.23 0.69 1.07

Arginine Arg R Basic Hydrophilic (-26 at pH = 2; -14 at pH = 7)

1.8 9.0 12.5 174.2 1.21 0.84 0.90

Aspartate Asp D Acidic Neutral at pH=2 (-18), Hydrophilic at pH=7 (-55)

2.0 9.9 3.9 133.10 0.99 0.39 1.24

Glutamate Glu E Acidic Neutral at ph=2 (8), Hydrophilic at pH=7 (-31)

2.1 9.5 4.1 147.13 1.59 0.52 1.01

Asparagine Asn N Acidic, polar Hydrophilic (-41 at pH = 2; -28 at pH = 7)

2.1 8.7 -- 132.118 0.76 0.48 1.34

Glutamine Gln

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4 years ago

Match the type of of evidence for evolution with the correct example. analogous structures vestigial structures homologous struc

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• Homologous structures: Both Ostriches have wings similar in form to those of their ancestors, but that do not allow the birds to fly.

Homologous structures are those that have structural similarities but are different in function. For example, if we look at the anatomical structure of a bird’s wing, it is very similar in structure with a human arm. However, over the course of time they have evolved to perform different functions.

• Vestigial structures: The inner ear bones of mammals have evolved from bones that form the jaws of reptiles.

Vestigiality refers to the process in which some structure lose their function over the course of evolution in some specie but they are functionally normal in other species. Such a structure is the inner ear bones of mammals which donot perform an important function in mammals but do perform in reptiles.

• DNA sequence data: Both Genes involved in RNA replication are conserved among bacteria and animals, suggesting a common evolutionary origin.

The sequencing of genetic data is an excellent method of finding the evolutionary histories and relatedness of different organisms. This field of sciences is called phylogenetics and the mentioned example is the result of phylogenetics.

• Analogous structures: The jointed legs of insects and vertebrates arose independently, indicating a different evolutionary origin.

Analogous structures are those that have similar function but they look very different in structure or anatomy. This is because they have been evolved from different ancestors and perform different functions. One example of these structures is mentioned, The jointed legs of insects and vertebrates that look different bur perform same function.

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4 years ago

Which of the following medial temporal lobe structures is important for declarative memory consolidation? Choose the correct opt

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Answer:

all choices are correct

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