Inheritance, variation and evolution Flashcards
What is a gamete?
A cell with half the number of chromosomes of the parent cell.
Name the male and female gametes in a) a human
b) a daisy plant
a) Male = sperm Female = egg
b) Male = pollen Female = egg
Name the shape which best describes the DNA polymer.
Double helix
How is DNA organised inside the cell nucleus?
Arranged in chromosomes
Which is larger, a chromosome or a gene?
Chromosome
What does a gene code for?
A particular sequence of amino acids
Write down the definition of the genome of a horse.
All the genetic material of the horse.
List two reasons why it is important to understand more about the human genome
- To be able to identify the genes which are linked to different diseases
- To understand and be able to treat inherited disorders
- To use in tracing human migration patterns from the past.
What are three advantages of sexual reproduction?
- Produce variation in the offspring
- If environment changes can give a survival advantage meaning some organisms are likely to survive
- Humans can speed up natural selection by selective breeding to increase food production
What are three advantages of asexual reproduction?
- Only one parent needed
- More time and energy-efficient as do not need to find a mate
- Faster than sexual reproduction
- Many identical offspring can be produced when conditions are favourable
List three organisms which reproduce using both sexual and asexual reproduction.
- Malarial parasites
- Fungi
- Strawberry plants
- Daffodils
Where would you find a nucleotide?
DNA
What does a nucleotide consist of?
Common sugar, phosphate group, base
What are the symbols of the 4 bases found in DNA?
A
T
C
G
What does the code for an amino acid consist of?
A sequence of three bases
Fill in the missing terms:
The long strands of DNA are made of alternating _____ and ______ sections.
Attached to each ________ is one of the four bases.
The DNA polymer is made up of repeating ____________ units.
Fill in the missing terms:
The long strands of DNA are made of alternating __sugar___ and __phosphate____ sections.
Attached to each __sugar____ is one of the four bases.
The DNA polymer is made up of repeating _____nucleotide_______ units.
In the complementary strands of DNA – which base is T always linked to?
A
Which organelle in the cytoplasm carries out protein synthesis?
Ribosome
What do carrier molecules bring to the organelle from the cytoplasm?
Amino acids
What happens in protein synthesis once the protein chain is complete?
The protein folds up into a unique shape.
What happens if a mutation codes for a slightly altered enzyme protein with a different shape?
The enzyme may no longer fit the substrate binding site
What can non-coding parts of DNA do?
Switch genes on or off and affect how genes are expressed
Complete the sentences below using one of the following words:
genotype phenotype homozygous gamete chromosome
The same alleles for a particular characteristic are described as _______ .
Mice fur can be described by its colour. This is known as the ______ .
The alleles for a particular characteristic determine its ______ .
The pollen of a rose plant can also be described as a male ______ .
The same alleles for a particular characteristic are described as homozygous
Mice fur can be described by its colour. This is known as the phenotype
The alleles for a particular characteristic determine its genotype
The pollen of a rose plant can also be described as a male gamete
What are the different forms of a gene called?
Alleles
Why is it easy to describe an organism’s phenotype for a particular characteristic but very difficult to state the genotype?
Most characteristics are a result of multiple genes interacting.
If two heterozygous tall plants were crossed 75 times, what proportion of the offspring would you expect to be short?
25% or 19
What is polydactyly and is it caused by inheriting a recessive or dominant allele?
A genetic disorder which results in having extra fingers or toes - dominant allele
How many chromosomes does this person have in a normal body cell?
23 pairs or 46
Is someone who is heterozygous for cystic fibrosis healthy?
Yes, they are a carrier but do not suffer from CF themselves
Many people feel opposed to the screening of embryos to identify the CF allele.
Suggest two reasons why they may feel this way.
- Screening procedure may cause miscarriage or damage embryo/fetus
- The embryo has a right to life
- Screening is expensive and could be used for other purposes
- Have to make moral/ethical or religious decisions as a result such as whether to terminate.