Development

Question 1

Define zygote

Answer 1

A fertilized egg. A diploid cell resulting from the fertilization of haploid gametes from the male and female lines

Question 2

Define gestation

Answer 2

In human development, the period required for embryonic and fetal development in utero; pregnancy

Question 3

What is the difference between the gestational calendar and gestation

Answer 3

the gestational calendar is usually 40 weeks. it begins on the first day of the mothers last menstrual period
Gestation only lasts 38 weeks, 2 weeks after ovulation occurs

Question 4

Explain the timing of the embryonic period

Answer 4

Embryonic period is the first 8 weeks following fertilization

Question 5

Explain the timing of fetal periods

Answer 5

Fetal period extends from the end of the embryonic period to birth

Question 6

Describe fertilization

Answer 6

Fertilization is when a sperm combines with an oocyte

Question 7

Where does fertilization occur?

Answer 7

Fertilization occurs in the ampulla of the uterine (fallopian) tube and fuse to form a single cell called a zygote

Question 8

What is a haploid cell?

Answer 8

A haploid has half of the usual genetic material. ex: sperm or oocyte

Question 9

What is a diploid cell?

Answer 9

A diploid has a complete set of chromosomes. Half from the mother and half from the father

Question 10

How many days can sperm survive in the uterine tube?

Answer 10

Sperm can survive in the fallopian tube for up to 5 days

Question 11

Describe capacitation

Answer 11

Priming of the sperm.
The process that occurs in the female reproductive tract where sperm are prepared for fertilization.

Question 12

What does capacitation lead to?

Answer 12

Capacitation leads to increased motility of the sperm and changes in their outer membrane that improve their ability to release enzymes capable of digesting an oocyte’s outer layers

Question 13

Describe the basics of sperm and egg fusion

Answer 13

After capacitation, the sperm releases enzymes allowing the sperm to penetrate the egg’s protective layers and fuse with the egg’s membrane. The sperm’s pronucleus then enters the egg, and the haploid nuclei of both fuse, completing fertilization. The result is a diploid zygote

Question 14

Explain fraternal twins

Answer 14

If two eggs are released during ovulation and both are fertilized it leads to two separate zygotes

Question 15

Explain identical twins

Answer 15

If after fertilization of a single egg, a cell can split away from the developing embryo, this leads to 2 separate but genetically identical monozygotic or identical twins

Question 16

Describe the basics of in vitro fertilization

Answer 16

1. Eggs are collected after ovulation or directly from the follicles. Sperm are collected and concentrated
2. The eggs and sperm are mixed in a Petri dish, allowing for fertilization
3. The fertilized zygote is then removed from the Petri dish for implantation
4. The zygote is then surgically implanted into the endometrium of the uterus.
   After successful implantation, the zygote should develop normally, as if it had been fertilized in the females oviducts

Question 17

Describe morula

Answer 17

The solid ball of cells that continues to move through the fallopian tube
5 days after fertilization, the morula reaches the uterus and begins to form a hollow space at its center

Question 18

Describe blastocyst

Answer 18

After the morula reaches the uterus the conceptus is called a blastocyst
The cells of the blastocyst can be divided into the cells that form the ball trophoblast cells

Question 19

Define gastrulation

Answer 19

The cells of the epiblast become the ectoderm. This process of forming a three layered disc is referred to as gastrulation and is technically the beginning of the embryonic period and the beginning of organogenesis

Question 20

Define organogenesis

Answer 20

The process where the 3 germ layers (endoderm, mesoderm, ectoderm) in a developing embryo differentiate and develop into the internal organs and tissues of an organism

Question 21

State the function of the placenta

Answer 21

Provides nutrients and oxygen, while eliminating wastes for the fetus

Question 22

Describe hCG

Answer 22

• Human Chorionic Gonadotropin
• Secreted by the trophoblast causes the corpus luteum to survive and continue producing progesterone and estrogens
  -hCG also stimulates the male fetal gonads to secrete testosterone for the development of the male reproductive system

Question 23

Describe the positive feedback loop of childbirth

Answer 23

As labor nears, oxytocin releases which begins to stimulate contractions
This causes the baby to push down, stretching the cervix.
The stretching of the cervix signals the release of more oxytocin which triggers more powerful contraction, and the cycle continues until birth

Question 24

List the 3 stages of childbirth

Answer 24

1. cervical dilation
2. expulsion of the newborn
3. afterbirth

Question 25

Describe the milk let-down reflex

Answer 25

In response to the oxytocin secretion in birth, the alveoli and ducts contract causing milk to drain into the mammary ducts which is suckled by the infant. Another example of a positive feedback loop

Question 26

Do male or female provide the chromosome that determines the genetic sex of the baby?

Answer 26

The male has XY chromosomes Females have XX chromosomes. The female will always pass on the X and the male will determine the second chromosome (X or Y) determining the sex

Question 27

Describe a Punnett square

Answer 27

A diagram used to illustrate the possible combinations of genes in an offspring if we know the genotype of the parents

Question 28

Describe autosomal dominant

Answer 28

Pattern of dominant inheritance that corresponds to a gene on one of the 22 autosomal chromosomes

Question 29

Describe autosomal recessive

Answer 29

Pattern of recessive inheritance that corresponds to a gene on one of the 22 autosomal chromosomes An autosomal recessive trait will only be expressed if 2 recessive alleles are inherited

Question 30

Define genotype

Answer 30

The complete genetic makeup of an individual

Question 31

Define phenotype

Answer 31

Physical or biochemical manifestation of the genotype; expression of the alleles