Exam 4

Question 1

Describe in order major steps in animal evolution and extinction

Answer 1

The development of oxygenic photosynthesis led to the Cambrian(寒武纪)explosion when many
shelled marine invertebrates diversified. The first vertebrate animals were fish and the first land tetrapods were amphibians. Reptiles acquired adaptations that allowed them to live and reproduce without access to water. The extinction of the dinosaurs was followed by the diversification of birds and mammals.

Question 2

Explain how gas exchange occurs in humans and why it is related to the cardiovascular system

Answer 2

noses and mouth to trachea –> divide to brachial tubes –> pass to lung, divided to branchioles, end to alveoli –> though capillaries to blood –> leave lung to hear to rest of body

gas exchange transfer oxygen and nutrients to all living cell
cardiovascular consisted by living cell

Question 3

Describe generally how the human heart works and how blood is circulated in a human body

Answer 3

From the right atrium to right ventricle–> capillaries and lungs where it is oxygenated —> into the left atrium then left ventricle where it is pumped to capillaries in the body —> deoxygenated blood is then returned to the right atrium.

Question 4

Describe the parts of the human digestive system and what the parts do

Answer 4

Ingestion(mechanical digestion) —> Digestion(chemical digestion - enzymes ) —> Absorption(nutrient molecules enter body cells) —> Elimination(undigested material)

Question 5

Explain the central dogma in biology and how this process differs between prokaryotes and eukaryotes

Answer 5

• The central dogma in biology is the concept that DNA codes for RNA which codes for proteins. One gene codes for one polypeptide.
• Eukaryotic mRNA has to be processed before translation
• prokaryotes’ happen inside of the cytoplasm,

Question 6

Transcription

Answer 6

synthesis of messenger RNA(mRNA) using information in DNA

Question 7

RNA processing

Answer 7

special nucleotides added to each end (5’ cap and poly-A tail)

Question 8

Translation

Answer 8

synthesis of a polypeptide using information in the mRNA

Question 9

Translation occurs in Cytoplasm. Translation happens in ribosome organelles.

Answer 9

Translation occurs in Cytoplasm. Translation happens in ribosome organelles.

Question 10

In translation, mRNA base triplets (codons) are read in 5’ to 3’ direction. Each codon specifies an amino acid. tRNA(transfer RNA) has an anticodon on one end(complement to codon) and a corresponding amino acid on the other end and adds amino acids to growing polypeptide chain.

Answer 10

In translation, mRNA base triplets (codons) are read in 5’ to 3’ direction. Each codon specifies an amino acid. tRNA(transfer RNA) has an anticodon on one end(complement to codon) and a corresponding amino acid on the other end and adds amino acids to growing polypeptide chain.

Question 11

Pleiotropy

Answer 11

Some genes affect many different characteristics, not just a single characteristic

Question 12

Epistasis

Answer 12

The alleles of one gene may mask or conceal the alleles of another gene

Question 13

Describe the 10 major stages that led to more complex life

Answer 13

1. life’s origin
2. Capturing the sun’s energy
3. a large more complex cell - development of the larger eukaryotic cell, having a nucleus
4. multicellular life - larger, multi celled organisms
5. animal arrive - oxygen pressure allowing respiration to power both larger creatures and
   more active pursuit in the animal world
6. plants pioneer the land
7. vertebrates conquer the land
8. flowers, fruits and grass
9. a two0legged primate gets really smart
10. Human culture evolves progressively