Questions and Answers
How many human babies are born each day?
365,000
What is DNA 'very good' at?
making copies of itself
What risk is there for a species that only reproduces by cloning?
If one person has a weak immune system, one successful parasite could wipe us all out
How does the DNA of sexually produced offspring compare to the DNA of the parents?
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How many sperm are produced by the average human male?
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What process is used to make sperm cells and egg cells?
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What happens to the genes when two chromosomes 'embrace'?
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What is the advantage of diversity within a species?
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When does a human female produce her eggs?
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What danger confronts sperm in the vagina?
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What does the sperm need to be allowed through the egg's zona?
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How much time passes between fertilization and the first division of the zygote?
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After fertilization, how long does it take for the blastocyst to arrive in the uterus?
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What risk does the blastocyst face after it attaches to the uterus?
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True or False: All cells have the same genes
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What does a gene do when it has been turned on?
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Where specifically does the baby get its nutrients from?
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Does the blood of the mother and the baby ever mix?
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How old is the fetus when it gains the ability to hear sound?
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What is the main job of the fetus during the last trimester?
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Study Notes
Reproduction and Development
- 365,000 human babies are born each day, indicating high reproductive rates globally.
- DNA is highly efficient at self-replication, ensuring genetic information is preserved across generations.
- Cloning as a reproduction method poses risks; a single pathogen could devastate a species with shared weak immune systems.
- Offspring from sexual reproduction inherit an equal contribution of DNA (50%) from each parent.
- An average male produces around 200 million sperm, highlighting the competition for fertilization.
- Gametes (sperm and egg cells) are produced through the process of meiosis.
Genetic Exchange and Diversity
- Chromosomes can exchange DNA when they pair, increasing genetic variation.
- Genetic diversity within a species improves adaptability and survival, raising chances of speciation.
- Females produce their eggs while still in the fetal stage, emphasizing early developmental processes.
Fertilization and Early Embryonic Development
- Sperm encounters an acidic environment in the vagina, presenting a challenge for successful fertilization.
- For sperm to penetrate the egg's zona, specific protein matches are necessary, demonstrating biochemical compatibility.
- Approximately 24 hours elapse from fertilization to the first division of the zygote, marking the start of cell division.
- The blastocyst takes about 5 days to reach the uterus after fertilization, essential for implantation.
- Once implanted, the blastocyst may face immune rejection from the mother's body, posing a risk to development.
Genetics and Nutrition During Pregnancy
- Not all cells in an organism contain identical genetic material; different types of cells express specific genes.
- Gene activation involves loosening DNA, indicating that certain environmental factors play a role in gene expression.
- The placenta serves as the primary source of nutrients for the developing fetus.
- There is no mixing of blood between the mother and the fetus, ensuring a separate circulatory system.
Fetal Growth and Sensory Development
- A fetus develops the ability to hear sounds at around 5 months gestation, indicating advancements in sensory development.
- The primary task of the fetus during the last trimester is growth, preparing for birth and life outside the womb.
Studying That Suits You
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Description
Test your knowledge on key concepts from the PBS-NOVA documentary 'Life's Greatest Miracle'. These flashcards cover topics such as human reproduction, DNA functions, and the implications of cloning in species. Perfect for students and biology enthusiasts alike!
