B13 - Reproduction Flashcards
What is sexual reproduction and why is it important?
Sexual reproduction involves the fusion of male and female gametes, producing genetically varied offspring. This variation increases the chances of survival if the environment changes and enables selective breeding.
What is asexual reproduction and its key advantages and disadvantages?
Asexual reproduction involves only one parent and produces genetically identical offspring (clones).
Advantages: Fast, no need for a mate, lots of offspring quickly.
Disadvantages: No genetic variation, making adaptation to changing environments harder.
Which organisms can reproduce both sexually and asexually?
Plants: Strawberries (runners), daffodils (bulbs)
Fungi: Spores (asexual and sexual reproduction)
Malaria parasite: Asexually in human liver/blood, sexually in mosquitoes
What is meiosis and why is it important in reproduction?
Meiosis is a type of cell division that produces gametes with half the number of chromosomes (haploid cells). It ensures genetic variation and maintains chromosome numbers across generations.
Describe the stages of meiosis.
Chromosomes are copied
Cell divides twice to form four genetically different gametes
Each gamete has a single set of chromosomes (haploid)
How does fertilisation restore the full number of chromosomes in humans?
Fertilisation fuses two haploid gametes (sperm and egg) to form a diploid zygote, restoring the full chromosome number (46 in humans).
Compare meiosis and mitosis
Meiosis: Produces 4 genetically different haploid gametes; used for sexual reproduction.
Mitosis: Produces 2 identical diploid cells; used for growth, repair, and asexual reproduction.
What is DNA and what is its structure?
DNA (Deoxyribonucleic acid) is a polymer made of two strands coiled into a double helix, carrying genetic information.
What is the genome and why is it important?
The genome is the entire genetic material of an organism. Understanding the human genome helps identify genes linked to diseases, aids in treatment development, and can track human migration.
What is a gene and what does it do?
A gene is a short section of DNA that codes for a specific protein, controlling an organism’s development and functioning.
What are the four DNA bases and how do they pair?
Adenine (A) pairs with Thymine (T)
Cytosine (C) pairs with Guanine (G)
What is a chromosome and how many do humans have?
A chromosome is a structure made from DNA found in the nucleus. Humans have 46 chromosomes, arranged in 23 pairs.
What is an allele?
An allele is a different version of the same gene.
What’s the difference between dominant and recessive alleles?
Dominant alleles always show their effect if present (written as capital letters).
Recessive alleles only show their effect when two copies are present (written as lowercase letters).
Define homozygous and heterozygous.
Homozygous: Two identical alleles (e.g., BB or bb)
Heterozygous: Two different alleles (e.g., Bb)
What is genotype vs phenotype?
Genotype: The genetic makeup (e.g., Bb)
Phenotype: The physical expression or traits (e.g., brown eyes)
What is a Punnett square and how is it used?
A Punnett square predicts the possible genotypes and phenotypes of offspring from a genetic cross.
What is cystic fibrosis and how is it inherited?
Cystic fibrosis is a genetic disorder affecting cell membranes, causing thick mucus. It is inherited in a recessive pattern (must inherit two faulty alleles).
What is polydactyly and how is it inherited?
Polydactyly causes extra fingers or toes and is inherited in a dominant pattern (only one faulty allele needed).
What is a genetic carrier?
A person who has one recessive allele for a disorder but does not show symptoms; they can pass the allele to their offspring.
What is embryo screening and why is it done?
Embryo screening checks embryos for genetic disorders before implantation (often during IVF) to reduce the chance of inherited diseases.
What are the ethical issues surrounding embryo screening?
Deciding what conditions to screen for
Concerns over selecting traits (“designer babies”)
What happens to unused embryos
Cost and accessibility
How is sex determined in humans?
By the sex chromosomes:
XX = female
XY = male
The father determines the sex of the offspring.
What is variation and why is it important in populations?
Variation results from differences in genetic material (due to meiosis and fertilisation) and is important for survival and evolution.
Why is sexual reproduction more advantageous in changing environments?
It produces genetic variation, giving some offspring a better chance of survival when conditions change.
How do malaria parasites reproduce?
Asexually in humans (liver and red blood cells)
Sexually in mosquitoes
What role does meiosis play in maintaining chromosome numbers across generations?
Meiosis halves the number of chromosomes in gametes so that fertilisation restores the diploid number, preventing chromosome doubling in each generation.
Why is understanding the human genome beneficial for medicine?
It helps identify genes linked to diseases, develop gene therapy, and create personalised medicine based on an individual’s genetic makeup.
Why does asexual reproduction produce clones?
It involves only one parent with no fusion of gametes, so offspring are genetically identical to the parent.
How does selective breeding use the principles of sexual reproduction?
It involves choosing parents with desirable traits to produce offspring with improved characteristics, speeding up natural selection.
what are the step in meiosis and the pneumonic to go with it.
Interphase (DNA replication)
Prophase
Metaphase
Anaphase
Telophase (then again for round 2
Interesting People Make Awesome Twins (IPMAT x2)
how to remember is cystic fibrosis and polydactyl are dominant or recessive?
🦶 Picture someone with Polydactyly waving “Hi” with extra fingers—easy to spot (dominant)!
🫧 Cystic Fibrosis is hidden in your body—hard to notice at first (recessive).
