Unit A Reproduction

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What is the ratio of males to females in the class? Is it the same
as the ratio for the entire human population? How are human
males and females different? What changes occur in humans
between fertilization and birth? What determines the gender
of a baby? Does reproduction always produce a healthy baby?
From the production of gametes to fertilization to birth,
complicated processes are involved. What if something
goes wrong? Can science and technology correct errors?
Scientists have always been interested in how life continues
from generation to generation. Technologies exist to improve
the success of reproduction in agricultural plants and animals.
Are there similar technologies available to humans? In this
chapter, you will learn about the specialized structures that
are used in sexual reproduction in humans, the development
of the embryo from zygote to birth, the mechanisms that
determine gender in humans, and the technologies that are
available to improve the success of human reproduction.
TRY THIS: Boy or Girl?
Skills Focus: predicting, conducting, recording
Toss a coin to explore the probability of having a boy or a girl.
Materials: 1 coin
1. Record the number of boys and girls in your class.
2. Create a data table similar to Table 1. Use it to record your
observations.
Table 1
Number Ratio of Ratio of
of tosses Prediction Heads (H) Tails (T) H to total T to total
10
3. Predict how many heads and tails will occur if you toss a
coin 10 times. Record your prediction.
4. Toss a coin 10 times. Record the results of each toss by putting
tally marks in the “Heads” or “Tails” column of your table.
A. Calculate the ratio of heads to total tosses and the ratio of
tails to total tosses. Are they the same?
B. Compare your ratios with your classmates’ ratios.
C. Record your ratios in a class data table.
D. Calculate the class ratios for both heads and tails.
E. How do your ratios compare with the class ratios?
F. Calculate the ratio of boys to girls in your class.
G. How does the coin-toss ratio compare with the boys-to-girls ratio?
NEL
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