Biology 1 blogs

18.1 Viruses
Why is a virus considered to be nonliving?

•Most people (biologists) consider viruses to be nonliving because they don't exhibit all the criteria for life. They don't carry out respiration, grow, or develop, all viruses can do is replicate and they can't even do that without the help of living cells.

What is the difference between a lytic cycle and lysogenic cycle?

•A lytic cycle is, the cycle which the new viruses can infect and kill other host cells. the Lysogenic is, the replication cycle in which the viruses nucleic acid is integrated into the host cell's chromosome.

What is a provirus?

•A provirus is viral DNA that is integrated into the host cell's chromosome.

How do retroviruses convert their RNA to DNA?

•Retroviruses convert their RNA to DNA by using, reverse transcriptase, an enzyme which is carried inside it's capsid. This enzyme helps produce double-stranded DNA from the viral RNA. Then the double-stranded viral DNA is integrated into the host cell's chromosome and becomes a provirus.

Describe the state of a herpes virus in a person who had cold sores several years ago but who does not have them now.

•If a person had cold sores several years ago, but no longer has it now means that this disease is going through the lysogenic cycle, meaning that the virus may seem to be gone but in reality it's just waiting to repeat it's cycle again.

17.1 Classification
1.For what reasons are biological classification systems needed?

• Biological classification is utilized by scientists to better understand organisms so that they can organize them.

2. Give two reasons why species binomial nomenclature is useful.

• To identify but as well for conversation, characteristics, and to help identify the genus of the organism.

3. Describe what Linnaeus contributed to the field of taxonomy.

• Linnaeus's systems was based on physical and structural similarities of organisms. Example: He might used the similarities in flower parts as a basis for classifying flowering plants.

4. What are the taxa used in biological classification?

• Taxa is used in biological classification to identify plants, and animals.

Which taxon contains the largest number of species?

• The broader a taxon, the more general it's characteristics, and the more species it contains.

Which taxon contains the fewest number of species?

• The smallest taxon is species.

5. Use categories that parallel the taxa of a biological classification system to organize the items you can borrow from a library.

17.2 The Six Kingdoms
1. How do members of the different kingdoms obtain nutrients?

• In general, differences in cellular structures and methods of obtaining energy are the two main characteristics that distinguish among the members of the six kingdoms.

2. Make a list of the characteristics that archae bacteria and eubacteria share. Then make a list of their differences.
Archae bacteria/Eubacteria-similarities

• Both have genes in similar structure,
• both are prokaryotic, so they don't have a nucleus,
  
• both have circular chromosomes, and their ribosomes are fundamentally similar in structure.

Archae bacteria/Eubacteria-differences

• Eubacteria has less complex genetic makeup, than Archae bacteria,
• Archae bacteria can obtain energy through methanogenesis as fore Eubacteria cannot,
• Archae bacteria are not pathogenic where, Eubacteria aren't.
  

3. What does it mean for species to have an evolutionary relationships?

• It means having the abiltity to interbreed, and having common similar gene sequences, which are determined by sequencing genes.

Identify five ways these relationships are determined. Describe each briefly and give an example for each.
They are identified by these five ways as follows:

• Structure similarities-occurrs among species which reveal relationships,
• Example- the presence of many physical structures.

• Breeding behavior-sometimes provides important clues to relationships among species
• Example-two species of frogs, Hyla versicolor and Hyla chrysoscelis, live in the same area and look similar.

• Geographical distribution- the location of species on Earth that helps biologists determine their realtionships with other species.
• Example-many different species of finches live on the Galapagos Islands off the coast of South America.
  

• Chromosome comparisons-both the number and structure of chromosomes, as seen during mitosis and meiosis, provide evidence about relationships among species.

• Example-Cauliflower, Cabbage, Kale, and Broccoli look different but have chromosomes that are almost identical in structure.

• Biochemistry-powerful evidence about relationships among species comes from biochemical analysis of organisms.
• Example-the DNA sequence in giant panadas and red panadas differ.

4. How do cladograms and fan-like diagrams differ?

• Cladograms is a model of the phylogent of a species, while fan-like diagrams, only help find realtionships between modern and extinct species.

5. Why is phylogenic classification more natural than a system based on characteristics such as medical usefulness, or the shapes, sizes, and colors of body structures?

• A phylogenic classification is more natural than a system based on similar characteristics because phylogenic classification is the sum of their genes.