Module 4 - Genetic info, variation and relationships between organisms

Question 1

Biodiversity

Answer 1

Variety of habitats and species in an area

Question 2

Species diversity

Answer 2

Number of different species and individuals in a species

Question 3

Genetic diversity

Answer 3

Variety of alleles in a population

Larger number of individuals in a species, larger the genetic diversity

Question 4

Benefits of high species diversity

Answer 4

Stable ecosystem
Species less likely to become extinct
Extinction won’t affect food chain as there are other species available

Question 5

How to measure species diversity

Answer 5

Species diversity index
Diversity = N(N-1) / £n(n-1)
N = number of individuals in a population
n = number of individuals in a species
£ = sum of

Question 6

How does deforestation lower species diversity

Answer 6

Decrease plant species diversity
Less variety of habitats
Less variety of food sources
Decrease animal species variety

Question 7

How does farming lower species diversity

Answer 7

Deforestation for space for farm
Only grow a few plants and animals and selectively breed
Pesticides to kill other species

Question 8

What is natural selection and adaptation

Answer 8

Variation in population of a species
Random mutation = new allele
Selection pressure applied
New allele means better chance of survival
Reproduction so frequency of new allele increases
At expense of old allele

Question 9

Stabilising selection

Answer 9

Environment favours most common characteristic
Extremes die out
Birth weight

Question 10

Directional selection

Answer 10

Favours an extreme
Over time becomes most common characteristic
Normal distribution shifts to that extreme
Antibiotic resistance

Question 11

What is a gene

Answer 11

Section of DNA coding for a protein

Question 12

What are genes made of

Answer 12

Introns (non-coding)

Exons (coding)

Question 13

How does a gene code for a protein

Answer 13

Made out of a sequence of bases
3 bases code for 1 amino acid
sequence of bases determine triplet codes
Determine sequence of amino acids

Question 14

Properties of triplet code

Answer 14

Degenerate = each amino acid has more than 1 triplet code
Non-overlapping = each base is only read once
Universal = each base sequence codes for the same amino acid in all species

Question 15

Types of mutations

Answer 15

Insertion
Deletion
Substitution

Question 16

DNA VS RNA

Answer 16

Deoxyribose vs ribose sugar
Thymine vs uracil
Double stranded vs single stranded
One type vs 2 types

Question 17

mRNA

Answer 17

Messenger RNA
Single stranded complementary copy of a gene
Carries code for assembling protein (codon)

Question 18

tRNA

Answer 18

Transfer RNA
Single stranded RNA folded and held by hydrogen bonds between bases
Amino acid attachment site on top
3 specific bases on bottom (anticodon)
Anticodon binds to complementary codons on mRNA

Question 19

Transcription (not process)

Answer 19

Occurs in nucleolus
Produces mRNA
Template strand used to build mRNA

Question 20

Transcription process

Answer 20

DNA helicase breaks hydrogen bonds between bases
Strands separate
Complementary bases bind to bases on the template strand
RNA polymerase joins sugar phosphate backbone
pre-mRNA spliced to remove introns
Leaves nucleus towards ribosome

Question 21

Translation (not process)

Answer 21

Takes place on ribosomes of rough endoplasmic reticulum

Uses sequence of codons on the mRNA to assemble the protein

Question 22

Translation process

Answer 22

mRNA leaves nucleus via nuclear pore
Attaches to ribosome
Complementary tRNA carrying specific amino acids bind to codons with their anticodons
Another tRNA molecule binds
Amino acids joined by peptide bonds
First tRNA molecule detaches from amino acid and leaves ribosome

Question 23

Role of ATP in protein synthesis

Answer 23

Adding an amino acid to a tRNA molecule