LIVING ENVIRONMENT 2015 - 2016

Name Class Date
11.4
Lesson Objectives
Lesson Summary
Homologous chromosomes are pairs of chromosomes that correspond in body cells. One chromosome from each pair comes from each parent.
A cell that contains both sets of homologous chromosomes has a diploid number of chromosomes (meaning “two sets”).
Haploid cells contain only one set of chromosomes. Gametes are haploid.
Meiosis is the process that separates homologous pairs of chromosomes in a diploid cell, forming a haploid gamete. The phases are as follows:
Meiosis I, which is preceded by a replication of chromosomes. Its stages are
 Prophase I: Each replicated chromosome pairs with its corresponding homologous chromosome forming a tetrad.
During tetrad formation, alleles can be exchanged between chromatids, a process called crossing-over.
 Metaphase I: Paired homologous chromosomes line up across the center of the cell.
 Anaphase I: Spindle fibers pull each homologous pair toward opposite ends of the cell.

Telophase I: A nuclear membrane forms around each cluster of chromosomes.
Cytokinesis then occurs, resulting in two new cells. The resulting daughter cells contain chromosome sets that are different from each other and the parent cell.
Meiosis II: Chromosomes do not replicate.
 Prophase II: Chromosomes, each consisting of two chromatids, become visible.
 Metaphase II, Anaphase II, Telophase II, and Cytokinesis: These phases are similar to meiosis I. Four haploid cells form. They are the gametes. During fertilization, two gametes unite forming a zygote.
Mitosis is one cell division that results in two genetically identical diploid cells.
Meiosis is two cell divisions that result in four genetically different haploid cells.
Alleles tend to be inherited together if they are located on the same chromosome.
Chromosomes, not genes, segregate independently.
The farther apart genes are on a chromosome, the more likely is cross over.
Information on linkage and the frequency of crossing-over lets geneticists construct maps of the locations of genes on chromosomes.

Name
Class Date
For Questions 1 –8, write True if the statement is true. If the statement is false, change the underlined word to make the statement true.
1. The offspring of two parents obtains a single copy of every gene from each parent.
2. A gamete must contain one complete set of genes.
3. Genes are located at specific positions on spindles.
4. A pair of corresponding chromosomes is homozygous.
5. One member of each homologous chromosome pair comes from each gene.
6. A cell that contains both sets of homologous chromosomes is haploid.
7. The gametes of sexually reproducing organisms are haploid.
8. If an organism’s haploid number is 6, its diploid number is 3.
On the lines provided, identify the stage of meiosis I or meiosis II in which the event described occurs.
9. Each replicated chromosome pairs with its corresponding homologous chromosome.
10. Crossing-over occurs between tetrads.
11. Paired homologous chromosomes line up across the center of the cell.
12. Spindle fibers pull each homologous chromosome pair toward an opposite end of the cell.
13. A nuclear membrane forms around each cluster of chromosomes and cytokinesis follows, forming two new cells.
14. Chromosomes consist of two chromatids, but they do not pair to form tetrads.
15. A nuclear membrane forms around each cluster of chromosomes and cytokinesis follows, forming four new cells.

Name Class Date
16.
THINK VISUALLY Draw two homologous pairs of chromosomes (in different colors if you have them) in these diagrams to illustrate what happens during these three phases of meiosis.
17.
Identify which phase of meiosis is shown in the diagrams below.
Use this diagram to answer Questions 18
–20.
18.
What does the diagram show?
19.
During what phase of meiosis does this process occur?
20. What is the result of this process?

Name Class
21.
Complete the table to compare meiosis and mitosis.
Mitosis
Date
Meiosis
Form of reproduction
Number of daughter cells
Change in chromosome number
Number of cell divisions
Difference in alleles between parent cell and daughter cells
For Questions 22 –27, complete each statement by writing the correct word or words.
22. A diploid cell that enters mitosis with 16 chromosomes will divide to produce daughter cells. Each of these daughter cells will have chromosomes.
23.
If the diploid number of chromosomes for an organism is 16, each daughter cell after mitosis will contain chromosomes.
24. A diploid cell that enters meiosis with 16 chromosomes will pass through cell divisions, producing daughter cells, each with chromosomes.
25. Gametes have a number of chromosomes.
26.
If an organism’s haploid number is 5, its diploid number is
.
27. While a haploid number of chromosomes may be even or odd, a diploid number is always
.

Name Class
34.3
Date
Lesson Objectives
Describe the effects the sex hormones have on development.
Name and discuss the structures of the male reproductive system.
Name and discuss the structures of the female reproductive system.
Describe some of the most common sexually transmitted diseases.
Lesson Summary
Sexual Development Hormones released by the ovaries and testes cause sexual development during puberty , a period of rapid growth and sexual maturation that usually starts between the ages of 9 and 15. At the end of puberty, the male and female reproductive organs are fully developed and become fully functional.
The Male Reproductive System The main role of the male reproductive system is to make and deliver sperm.
The testes are the main organs of the male system. Two testes are held in an external sac called the scrotum . The testes make sperm in tiny tubes called seminiferous tubules . The sperm mature and are stored in an epididymis . A tube called a vas deferens carries sperm from each testis to the urethra within the penis.
Along the way, secretions of several glands form a nutrient-rich fluid called seminal fluid. The combination of sperm and seminal fluids is called semen . Semen leaves the body through the urethra. Contractions eject semen from the penis in a process called ejaculation.
A mature sperm cell consists of a head that contains the nucleus, a midpiece that is packed with mitochondria, and a flagellum that propels the sperm.
The Female Reproductive System The main roles of the female reproductive system are to make eggs and prepare the female body to nourish an embryo.
The ovary is the main organ of the female system. Each ovary has thousands of follicles, which are clusters of cells that surround an egg. A mature egg moves through the Fallopian tube to the uterus, which is connected to the outside of the body by the vagina.
Beginning in puberty, the female body goes through a menstrual cycle , a series of events that prepares the body to care for a fertilized egg. The menstrual cycle has four phases:
 Follicular phase: An egg matures in its follicle.
 Ovulation : The mature egg is released from the ovary.
 Luteal phase: The follicle develops into a structure called the corpus luteum .
 Menstruation : The lining of the uterus falls away and leaves the body through the vagina if the egg is not fertilized.
Sexually Transmitted Diseases A disease spread during sexual contact is called a sexually transmitted disease (STD). Bacteria and viruses can cause STDs. Chlamydia,

syphilis, gonorrhea, and AIDS are STDs.
Name
Class Date
For Questions 1 –3, write the letter of the correct answer on the line at the left.
1.
Male and female embryos are nearly identical until the
A.
second week of development. C.
third month of development.
B.
seventh week of development. D.
fifth month of development.
2.
Which hormone, when produced in an embryo, triggers a male pattern of development?
A.
testosterone
B.
progesterone
C.
D.
estrogen
adrenalin
3.
The period of human development that includes rapid growth and sexual maturation is called
A.
adolescence.
B.
childhood.
C.
D.
maturity.
puberty.
For Questions 4 –8, match each structure of the male reproductive system with its description.
Structure Description
4.
epididymis
5.
scrotum
6.
seminiferous tubule
A.
External sac that holds male gonads
B.
The primary male reproductive organ
C.
Structure in which sperm mature
7.
testis D.
Structure in which meiosis occurs
8.
vas deferens E.
The tube through which sperm travel to the urethra
For Questions 9 –12, complete each statement by writing the correct word or words.
9.
The seminal vesicles, nutrient-rich fluid called
gland, and
fluid.
gland produce a
10.
Sperm mixed with the seminal fluid is called
11.
Signals from the
.
nervous system cause sperm to be ejaculated.
12.
The of a sperm cell contain mitochondria that supply energy to the
,which propels the sperm forward.
For Questions 13 –16, complete each statement by writing the correct word or words.
13.
The primary reproductive organs of females are the .
14.
The function of a(n)
15.
Only about mature ovum. is to help an egg mature.
of the 400,000 eggs a female is born with develop into a
16.
The structure of the female reproductive system in which the embryo develops is called the .

Name Class Date
For Questions 17 –20, match each phase of the menstrual cycle with the correct event.
Phase Event
17.
Follicular phase A.
An unfertilized egg leaves the body.
18.
Ovulaton
19. Luteal phase
B.
The egg travels through a Fallopian tube.
C.
An egg within a follicle develops.
20.
Menstruation D.
An egg is released from an ovary.
21.
Complete the concept map to explain what the outcomes of a menstrual cycle can be.
Mature ovum enters the
Fallopian tube
No sperm are in female tract
Fertilization could result
For Questions 22 –24, write True if the statement is true. If the statement is false, change the underlined word or words to make the statement true.
22.
AIDS is the most common bacterial STD.
23.
Chlamydia damages the reproductive tract and can cause infertility.
24.
Apply the
Hepatitis B and genital herpes are viral STDs.
Big idea
25.
How is the menstrual cycle an example of the body’s use of negative feedback?

Name
Class Date
On the lines provided, label the structures of the male reproductive system that correspond to the numbers in the diagram.
1.
2.
3.
For Questions 4 –10, match the term with its definition.
Term Definition
4.
endocrine gland
5.
exocrine gland
6.
gastrulation
A.
Mixture of sperm and seminal fluids
B.
Attachment of the blastocyst to the uterine wall
C.
Discharge of uterine tissue and blood from the vagina
7.
hormone
8.
implantation
9.
menstruation
10.
semen
D.
Chemical made in one part of the body that travels in the bloodstream to other parts
E.
The process that produces the three cell layers of the embryo
F.
Type of gland that releases its chemicals directly into the bloodstream
G.
Type of gland that releases its chemicals out of the body

Name Class Date
34.4
Lesson Objectives
Describe fertilization and the early stages of development.
Identify the major events of later stages of development.
Lesson Summary
Fertilization is the joining of a sperm and an egg. Following fertilization, a series of events called development begins.
A fertilized egg is called a zygote . The zygote divides and undergoes repeated rounds of mitosis and develops into a hollow ball of cells called a blastocyst .
About a week after fertilization, the blastocyst attaches to the wall of the uterus in the process of implantation . At the same time, cells of the blastocyst start to specialize through differentiation. Some cells migrate to form two cell layers—the ectoderm and the endoderm.
A third layer of cells is produced by a process called gastrulation , in which cells from the ectoderm migrate to form the mesoderm. The three layers eventually develop into the different organs of the embryo.
During neurulation , the notochord and the neural tube form. The neural tube eventually develops into the brain and spinal cord.
As the embryo develops, membranes for protection and nourishment also form. Part of one membrane combines with the uterine lining to form the placenta . Mother and embryo/fetus exchange gases, food, and waste products across the placenta. The umbilical cord connects the embryo/fetus to the placenta.
After eight weeks of development, the embryo is called a fetus . By the end of three months, most organs are fully formed.
Another six months of development occurs before birth.
During months 4–6, the fetus’s tissues become specialized and organs such as the heart begin to function.
During months 7–9, the fetus’s organ systems mature as the fetus grows in size and mass. The lungs and the central nervous system complete their development.
Childbirth occurs about nine months after fertilization, when hormones cause contractions in the mother’s uterus. The contractions first push the baby out through the vagina. Then, more contractions expel the placenta and amniotic sac from the uterus. Shortly after birth, the mother’s breast tissue begins to produce milk that contains everything the baby needs for the first months of life.
The placenta is a barrier to many harmful agents, but some are able to pass through it, such as viruses that cause AIDS and German measles. Alcohol, drugs, and smoking also have negative effects on embryos and fetuses. Prenatal care and advancements in medical technology have lowered the infant mortality rate.

Name Class
Date
For Questions 1 –4, complete each statement by writing the correct word or words.
1.
The fusion of a sperm with an egg is called .
2.
During implantation, the
3.
Embryonic structures called
embeds itself into the lining of the uterus.
4.
The embryo is surrounded by fluid called the
combine with the uterine lining to form the
fluid.
5.
Complete the table by identifying events and structures of early development.
Event or Structure What It Is
The process in which sperm joins an egg
Gastrulation
The layer of cells that develops into the skin and nervous system
Early stage in the development of the nervous system
Endoderm
Fluid-filled structure that cushions and protects the embryo
Embryo’s organ of respiration, nourishment, and excretion
Mesoderm
Umbilical cord
6.
What major changes occur in a developing fetus during months 4–6 of pregnancy?
7.
What major changes occur in a developing fetus during months 7–9 of pregnancy?
.

For Questions 8 –13, write the letter of the correct answer on the line at the left.
8.
The contractions of labor before childbirth are triggered by
A.
the amniotic fluid.
B.
the hormone oxytocin.
C.
the umbilical cord.
D.
the uterine wall.
9.
The term “afterbirth” refers to the
A.
amnion and the chorion.
B.
clamping of the umbilical cord.
C.
placenta and amniotic sac.
D.
production of milk for the baby.
10.
What is a belly button?
A.
a structure with an unknown purpose
B.
a scar left from the umbilical cord
C.
remains of the notochord
D.
the point where implantation occurred
11.
Which hormone causes the mother’s breast tissue to begin producing milk?
A.
estrogen
B.
oxytocin
C.
progesterone
D.
prolactin
12.
Using alcohol during pregnancy can harm a developing embryo, especially its
A.
reproductive system.
B.
circulatory system.
C.
endocrine system.
D.
nervous system.
13.
Which public health measure has decreased the incidence of spina bifida?
A.
the addition of folic acid to grain products
B.
the development of new types of baby formula
C.
the programs aimed at reducing smoking and alcohol use
D.
the use of a vaccine that prevents German measles
Apply the Big idea
14.
Women with Type 1 diabetes may face challenges controlling blood sugar levels during pregnacy. Early in pregnancy, the developing fetus removes glucose from the mother’s blood at a great rate. Would this raise or lower her need for insulin?

Name
28.3
Class Date
Lesson Objectives
Compare asexual and sexual reproduction.
Contrast internal and external fertilization.
Describe the different patterns of embryo development in animals.
Explain how terrestrial vertebrates are adapted to reproduction on land.
Lesson Summary
Most animals reproduce sexually. Some animals are also able to reproduce asexually.
Asexual reproduction requires only one parent allowing for rapid reproduction.
Sexual reproduction requires two parents. This type of reproduction maintains genetic diversity in a population by creating individuals with new combinations of genes.
In sexual reproduction, eggs and sperm meet either inside or outside the body of the egg-producing individual.
During internal fertilization, eggs are fertilized inside the body of the egg-producing individual.
In external fertilization, eggs are fertilized outside the body.
Embryos develop either inside or outside the body of a parent in various ways.
Oviparous species are those in which embryos develop in eggs outside the parents’ bodies.
In ovoviviparous species, embryos develop within the mother’s body, but they depend entirely on the yolk sac of their eggs.
Viviparous species’ embryos obtain nutrients from the mother’s body. Some mammals nourish their embryos by means of a placenta —a specialized organ that enables exchange of respiratory gases, nutrients, and wastes between the mother and her developing young.
As invertebrates, nonvertebrate chordates, fishes, and amphibians develop, they undergo metamorphosis , resulting in changes to their shape and form.
Some insects undergo gradual or incomplete metamorphosis. Immature forms, or nymphs , resemble adults, but they lack functional sexual organs and some adult structures.
Other insects undergo complete metamorphosis. Larvae change into a pupa , the stage in which an insect larva develops into an adult.
Chordates had to adapt to reproduction on land. Most chordates need a wet or moist environment for their eggs.
The eggs of most aquatic organisms must develop in water. Reptiles, birds, and a few mammals have evolved amniotic eggs in which an embryo can develop outside its mother’s body, and out of water, without drying out.
Mammals have various reproductive adaptations. But all mammalian young are nourished by milk produced by the mother’s mammary glands .

Name Class
Date
1.
What does asexual reproduction allow animals to do?
2.
What is an advantage of sexual reproduction?
3.
THINK VISUALLY Shade the arrows showing haploid stage of the life cycle. Draw small dots in the arrows showing diploid stages.
4.
What is the difference between external and internal fertilization?
Write the letter of the correct answer on the line at the left.
5.
In which mode of reproduction do the embryos develop inside the mother’s body using the egg yolk for nourishment?
A.
oviparous
B.
ovoviviparous
C.
D.
6.
Organisms that develop placentas are
viviparous
herbivorous
A.
oviparous.
B.
ovoviviparous.
C.
viviparous.
D.
herbivorous.
7.
Explain the difference between complete and incomplete metamorphosis.

Name Class
8. THINK VISUALLY
Date
9. Complete the table about mammal reproduction.
Types of Mammalian Reproduction and Development
Group How Are Young Born?
Marsupials
Young hatch from soft-shelled eggs laid outside the mother’s body.
How Are Young Fed?
Young drink from a nipple inside the mother’s pouch.
Placental mammals
Young are generally nursed by the mother.
Apply the Big idea
10.
How might the shape of an amniotic egg complement its function?

Name Class Date
24.1
Lesson Objectives
Identify the functions of various structures of a flower.
Explain how fertilization differs between angiosperms and other plants.
Describe vegetative reproduction.
Lesson Summary
Four different kinds of specialized leaves form flowers.
Sepals form the outermost circle of flower parts. They protect a flower bud.
Petals form a ring just inside the sepals. Some are brightly colored, which attracts pollinators.
Stamens are the male reproductive structures and form a ring inside of the petals. Pollen is produced in an anther, which is the sac at the tip of a stamen. Each pollen grain contains a male gametophyte.
Carpels are the female reproductive structures at the center of flowers. The female gametophytes develop inside the ovules that form in a carpel’s ovary.

The sticky tip of a carpel, called the stigma, captures pollen.

A pistil is a structure that is made up of one or more carpels.
The life cycle involves alternation of generations. Meiosis in stamens and carpels produces haploid cells (spores) that develop into gametophytes.
The haploid cells in a stamen’s anther undergo mitosis and form pollen grains, the male gametophytes, that contain 2 sperm nuclei.
A haploid cell in each ovule of a carpel undergoes mitosis to produce an embryo sac, or female gametophyte, which contains 8 haploid nuclei. One of these nuclei becomes the egg.
Pollen grains are transported to the stigmas of carpels during pollination.
Both sperm nuclei fuse with nuclei in the embryo sac in a process called double fertilization.
One sperm fuses with the egg to form a diploid (2N) zygote. The other sperm fuses with 2 other nuclei to form the triploid (3N) endosperm.
Asexual reproduction is common in plants.
Vegetative reproduction leads to offspring that are identical to the parent. The offspring develop by mitotic cell division of cells in stems, leaves, and roots.
Horticulturists use vegetative reproduction to propagate (grow) many identical plants. Making cuttings of stems and roots is one example. Grafting involves attaching a bud or a stem of one woody plant to the stems of another.

Name
Class
For Questions 1 –10, match the floral part with its description.
Floral Part Description
1.
anthers A.
Stalk with a stigma at the top
Date
2.
carpels B.
Structures that produce male gametophytes
3.
filament C.
Structure that contains one or more ovules
4.
ovary
5.
6.
petals
pollen
D.
Outermost circle of green floral parts
E.
Long, thin structure that supports an anther
F.
Floral parts that produce female gametophytes
7.
sepals G.
Yellowish dust that contains male gametophytes
8.
stamen H.
Male structure with an anther and a filament
9.
stigma I.
Brightly colored parts just inside the sepals
10.
style J.
Sticky, top portion of style
11.
Complete the illustration by labeling the parts of the flower indicated.
For Questions 12 –15, complete each statement by writing the correct word or words.
12.
13.
The body of an adult plant with flowers is the
The gametophytes of angiosperms have cells with nuclei that have the chromosomes.
generation of the plant’s life cycle.
number of

Name
14.
A male
Class Date
of an angiosperm is a pollen grain.
15.
A(n) contains a female gametophyte of an angiosperm.
For Questions 16 –20, write True if the statement is true. If the statement is false, change the underlined word or words to make the statement true.
16. In pollination, pollen grains are transferred to the ovary of a flower.
17. A pollen tube delivers one sperm to an ovule.
18. The fertilized egg in an ovule becomes the zygote of a new sporophyte.
19. Triploid tissue, called endosperm, forms in double fertilization.
20. A fertilized embryo sac then develops into a seed.
21. What is vegetative reproduction in plants?
22. Give an advantage and a disadvantage of vegetative reproduction to plants.
23. Complete the table to summarize asexual reproduction in plants.
Vegetative Reproduction in Plants
Reproductive Method Vegetative Parts Involved Example
Stolons
Tubers
Grafts
Apply the Big idea
24. How might a long period of rainy weather affect reproduction in wind-pollinated plants?