10B- Evidence of relatedness

Question 1

Structural morphology

Answer 1

The study of body structure to give insight into the relationship between species

Question 2

Species share a common recent ancestor if

Answer 2

If species have a similar set of proteins, chromosomes or DNA sequences, it is said that they shared a recent common ancestor

Question 3

Mutations can occur when

Answer 3

Mutations occur when DNA copying errors during replication are not corrected, leading to permanent changes in the DNA sequence.

Question 4

What happens during DNA replication that can lead to mutations?

Answer 4

Mutations occur when DNA is copied and errors in the copying process are not corrected. If these errors aren’t picked up, they become part of the genome.

Question 5

: How does the accumulation of mutations provide evidence of divergence between organisms?

Answer 5

The accumulation of mutations shows differences in DNA between organisms. More mutations indicate more divergence and that the divergence occurred longer ago.

Question 6

What does a high number of mutations in DNA suggest about the evolutionary relationship between organisms?

Answer 6

A high number of mutations suggests that there has been significant divergence between organisms, indicating that they diverged a long time ago.

Question 6

Structural morphology

Answer 6

The study of body structure to give insight into the relationship between species

Question 7

Homologous structures

Answer 7

are features found on different species that may look and function differently but have derived from a common ancestor eg. a dolphins flipper, cats leg, a birds wing and a humna arm

Question 8

What do homologous structures provide evidence of in terms of evolutio

Answer 8

Homologous structures provide evidence of divergent evolution, indicating that species share a recent common ancestor but have evolved different traits due to adaptation to different environments.

Question 9

What leads to the classification of organisms as different species despite sharing homologous structures?

Answer 9

Organisms are classified as different species when enough genetic differences accumulate, making them unable to interbreed and produce fertile offspring.

Question 10

Why might species with homologous structures be unable to interbreed?

Answer 10

They may be unable to interbreed due to genetic differences that have accumulated over time, which can lead to reproductive isolation.

Question 11

=What factors contribute to the divergence of species with homologous structures?

Answer 11

Divergence can result from adapting to different selection pressures or genetic drift, leading to variations in traits despite a common ancestry.

Question 12

Vestigial structures

Answer 12

Vestigial structures have no apparent function but can be used to determine ancient ancestors.

Question 13

Although vestigial structures have no function, they are not selected against-why is this the case

Answer 13

Vestigial structures persist because they are not selected against; they do not adversely affect the organism’s fitness or reproduction, so they remain in the genome.

Question 14

Molecular homology

Answer 14

The study of DNA and amino acid sequences to determine relatedness between species

Question 15

To determine the relatedness

Answer 15

we can compare the body stuctures of the species via structural morphology or the DNA and amino acid sequecnes via molecular homology

Question 16

The bigger the difference in amino acid sequences, the…

Answer 16

the longer the period of time that divergence would have occurred

Question 17

Haemoglobin

Answer 17

A PROTEIN responsible for carrying oxygen

Question 18

Defintion of homologus structure and example

Answer 18

are features found on different species that may look and function differently but have derived from a common ancestor.an example of a homologous structure pentadactyl

Question 19

What is the half life and dating period of the radioisotopic series below:

1.Carbon-14-nitrogen-14

2.Uranium-235-lead-207

3.Uranium-238-lead-206

4. Potassium-40-argon-40

Answer 19

Carbon-14-nitrogen-14 has a half life of 5730 years and a dating period of 1,000-50,000years.-seen in organic material

Uranium-235-lead-207 has a half life of 700 million years and a dating period of 1 million-4.5 billion years—seen in shells and corals

Uranium-238-lead-206 has a half life of 4.5 billion years and a dating period of 1 million to 4.5 billion years-seen in shells and corals

Potassium-40-argon-40 has a half life of 1.3 billion years and a dating period of 100,000 years+.— seen in Igneous(volcanic) rocks.

Question 20

examples of vestigal structures

Answer 20

Example: pelvic bone in a whale, coccyx in humans
Despite no function, these structures are not selected against

Question 21

Haemoglobin is made of

Answer 21

Made up of 4 polypeptide chains consisting of 146 amino acids.

Question 22

haemoglobin can be used to determine relatedness by

Answer 22

any proiten and heamoglobin can be used to dermitne the realtedness becuse its a protein and hecne it canbe used to compared the amount of amino acids and the amino acid sequences because the more related a species is, the more similar the amino acid sequences

Question 23

Compares ancestyr of humans and chimpanzees and kangaroos

Answer 23

Humans and chimpanzees have highest level of similarity suggesting they share the most recent common ancestor compared to kangaroos (more differences)

Question 24

Cytochrome C

Answer 24

Enzyme present in mitochondria made up of 104 amino acids
Assists in carrying electrons in aerobic and anaerobic reactions.

Question 25

Degeneracy

Answer 25

refers to the concept that mutiple codons can code for the same amino acid

Question 26

In point mutations, such as substitution mutations, how might a change in DNA not always lead to a change in the amino acid sequence? How does this affect the rate at which differences accumulate compared to changes in DNA?

Answer 26

point mutations, such as substitution mutation, a change in DNA may not change the amino acid sequence.

Therefore, a change in DNA doesn’t necessarily mean a change in amino acid sequence, consequently these differences accumulate more slowly that differences in DNA.

Question 27

How can we use DNA to determine relatedness

Answer 27

Nucleotide differences between organisms is used to determine relatedness

The greater percentage of DNA sequence in common, the more closely related
Humans and chimpanzee have 98% similarity in DNA

Question 28

DNA sequence is used to identify silent mutations due to the degeneracy of the geneitc code why

Answer 28

The degeneracy of the genetic code means that multiple codons can encode the same amino acid. Silent mutations occur when a DNA change results in a codon that still codes for the same amino acid, so the protein sequence remains unchanged. These mutations can be identified by analyzing the DNA sequence, as the protein sequence does not reflect the change.

Question 29

Why are amino acid sequences used to determine relatedness between distantly related species?

Answer 29

However, amino acid sequences are easier to interpret and therefore used to determine relatedness between distantly related species.

Question 30

How can genomes be used to determine relatedness?

Answer 30

genomes have DNA, therefore can be used to determine relatedness

Question 31

why does a sediment turn into sedimentary rock

Answer 31

sediment turns into sedimentary rock due to increased pressure

Question 32

fossils of species of fish are more likely to be found than fossils of land dwelling animals. explain why this is thie case with reference to two conditions required for the fossilisation of an organism

Answer 32

1. rapid burial of the remains in the ocean than on land due to more sediment accumulation and lower exposure to scavengers or decomposers
2. less oxygen in the aquatic environment and water is cooler—-expalin this and put this into mindmap

Question 33

Factors Favoring Fossilization

Question 34

Explain how scientists would have calculated the absolute age of the ancient mollusc fossils.

Answer 34

Scientists measure the amounts of a radioactive isotope and its decay product in the ancient mollusc fossils. By knowing the half-life of the isotope, they can calculate the time that has passed since the fossil was formed, providing the absolute age of the fossil.

Question 35

How can the absolute age of the ancient mollusc fossils be used to estimate the relative age of the ancient Osteichthyan fossil?

Answer 35

Using the law of fossil succession the relative age of the Osteichthyan fossil could be estimated from the absolute age of the molluscs.1Fossils found in the same layer as the molluscs are approximately the same age, whereas fossils in deeper layers are older, and higher layers are younger.2

Question 36

Describe one important step in evolution from ancient unicellular eukaryotes to Osteichthyans.

Answer 36

The Cambrian explosion (~535 mya), which describes a period of rapid diversification of multicellular life, characterised by the evolution of hardened body parts such as shells or bones.1

Question 37

What are 2 ways we can determine the relatedness between species

Answer 37

1. using structural morpolgy wich is the study of body structure to give insight into the relationship between species

2.Molecular homology which is the study of DNA and amino acid sequecnes to determine relatndenss between species