I.   Grade/Course Title: 7th Grade Science

 

      a. Course Overview/Description: ______________________________________________________

 

      b. Quarter: Two

 

II. Unit #4: Genetics and Reproduction     Unit Length: 5 weeks

                                                            

      a. Unit Introduction: In this unit students will describe the structure and function of the human reproductive system including the production of two special reproductive cells. These cells are formed by a type of cell division called meiosis.  That these cells contain only half the number of chromosomes found in other body cells and when these cells join through the process of fertilization they form one cell with a complete set of chromosomes. Furthermore, these chromosomes carry the genetic information necessary for the cells to function properly and the same genetic information also gives the individual, characteristics or traits. These traits are a combination of the parents resulting in variations from one generation to the next.

 

                                                                                                                                                                                                                                               

      b. Standards for Unit #4

·      C26. Describe the structure and function of the male and female human reproductive systems, including the process of egg and sperm production.

·      C27.  Describe how genetic information is organized in genes on chromosomes, and explain sex determination in humans.

 

CT State Grade Level Expectations (Draft)

GRADE-LEVEL CONCEPT 1: u Heredity is the passage of genetic information from one generation to another.

GRADE-LEVEL EXPECTATIONS:

1.    Living organisms must reproduce to continue the existence of their species.   Through reproduction new individuals which resemble their parents are formed.  All the organisms alive today arose from preexisting organisms.

2.    All the cells in a multicellular organism result from a single fertilized egg cell, through a process of continuous cell divisions (mitosis).  Instructions for how an organism develops are stored in DNA molecules which are part of the chromosomes inside the cell nucleus.

3.    The chromosomes occur in matching pairs, and each cell in a multicellular organism contains the number of chromosomes that are typical of that species.  For example, cells in human beings contain 23 pairs of chromosomes; 46 in all.

4.    Organisms grow by increasing the number of body cells. During mitosis, a body cell first duplicates the chromosomes and then divides into two daughter cells, each one with a complete set of chromosomes. 

5.    Most multicellular organisms reproduce by sexual reproduction, in which new cells are produced by the combination of two germ cells (gametes).  The cell division that produces the germ cells is called meiosis.  During meiosis, matching chromosomes in each pair separate from each other so that each germ cell contains only half of the chromosomes of the original cell.

6.     Meiosis and gamete formation takes place in the reproductive organs; testes in males produce the sperm and ovaries in females produce the eggs.

7.    In humans, the reproductive organs are in place at birth, but are readied to perform their reproductive functions by hormones released during adolescence. Males produce millions of sperm over the course of their adult life.  Females are born with a finite number of immature eggs in the ovaries that are released one at a time in a monthly cycle.

8.    In humans, if an egg is fertilized by a sperm in the female’s fallopian tube, the resulting zygote may develop into a fetus in the female uterus.  If the egg is not fertilized, it will leave the female’s body in a monthly discharge of the uterine lining (menstrual cycle).

9.    A segment of DNA that holds the information for a specific trait is called a gene.  Each chromosome in a pair carries the same genes in the same place, but there are different versions of each gene. 

10. In sexual reproduction, offspring of the same parents will have different combinations of genes and traits, creating genetic variability within the species. Sexual reproduction is the basis for the evolution of living organisms

CONTENT STANDARD 8.2 - continued

 

GRADE-LEVEL CONCEPT 2: u Some of the characteristics of an organism are inherited and some result from interactions with the environment.

1.     Gender in humans is a trait determined by genes carried by a special pair of chromosomes identified as “X” and “Y”.  Female gametes have only an “X” chromosome; male gametes can have either an “X” or a “Y”.  The sperm that fertilizes the egg determines the sex of the offspring: a zygote containing two X chromosomes will develop into a female and a zygote containing X and Y chromosomes will develop into a male.

Most human traits are inherited from parents, but some are the result of environmental conditions.  For example, eating and exercising habits may affect the body mass and shape of individuals in the same family.

     

c. Essential Questions:

1. How do humans reproduce?

2. Why are the reproductive structures different in males and females?

3. What are the reproductive cells called?

4. What are chromosomes and how do they carry genetic information?

5. How are reproductive cells formed?

6. What are characteristics or traits?

7. How are offspring different than their parents?

8. How are sex and variations determined?

 

 

 

 d. Essential Content/Concepts:

1.  The male reproductive system produces the sperm cell

2.  The female reproductive system produces the egg cell.

3.  Chromosomes carry the genetic information to produce new organisms.

4.  The two reproductive cells carry half the chromosomes necessary for human 

     development.

5.  Fertilization is the process that joins the two special reproductive cells.

6.  The offspring is not identical to either parent, but has traits of both.

7.  Sexual reproduction leads to variation in the next generation.

 

 

e. Essential Skills:

1.  Explain the differences between mitosis and meiosis.

2.  Describe the male and female reproductive system.

3.  Explain the difference between dominant and recessive genes.

4.  Describe how variations can be determined through genetics.

5.  Describe how chromosomes determine sex. 

6.  Use the information in a Punnett Square.

 

      f. Vocabulary –

sex cells, sperm, egg, uterus, testes, ovaries, fallopian tube, sperm duct, genetics, traits, dominant, recessive, chromosomes, genes, Punnett square, heredity, Mendel, meiosis, mitosis, genetic disorder, genetic diseases, genotype, phenotype

 

g. Science Misconceptions

1. Traits are inherited from one parent.

2. Development of the offspring takes place in the stomach.

3. Environmentally caused characteristics can be passed to offspring.

4. Meiosis does not differ from mitosis.

5. The role of chance and probability in heredity.

                           

           

Activities:

Labs:

Flower Fertilization and Flower Dissection

Mendelian Crosses

Bug Builders/Model Making

Punnett Squares

Probability Exercises

Tracing Traits

http://www.teachersdomain.org/resources/tdc02/sci/life/repro/lp_reproduce/

 

Projects:

Genetic Disorder Research Project

Reading for Information:

Clone Wars

 

UNIT RESOURCES:

            Readings, Texts, Materials, Videos

 

Suggested Science Fair Topics

 

Example Assessment Questions

 

  1. In humans, each egg and each sperm contain
  1. 23 chromosomes  b. 46 chromosomes  c. 69 chromosomes  d. 529 chromosomes

 

  1. Identical twins happen once in 250 births. How many pairs of these twins might be at a school with 2,750 students?

a. 1    b. 11      c. 22    d. 250

 

  1. Where do fertilization and implantation, respectively, take place?

a. uterus, fallopian tube        b. fallopian tube

c. uterus, vagina                   d. fallopian tube, uterus

 

  1. If there are 14 chromosomes in pea plant cells, how many chromosomes are present in a sex cell of a pea plant?

a. 21     b. 14.     c. 7     d. 4

 

  1. Use a Punnett square to determine the possible genotypes of the offspring of a BB x Bb cross.

a. all BB      b. BB, Bb     c. BB, Bb, bb      d. all bb

 

  1. Which sex chromosomes do females have? Which do males have?

 

 

  1. How are sex cells different from other body cells?