Zygote and Embryo formation

Question 1

What is a newly fertilized egg cell called?

Answer 1

A zygote

Question 2

What is the zygote? (N? 2N?)

Answer 2

Diploid (2N) bc 2 sets of chromosomes are being joined together

Question 3

What are the two types of fertilization? Which organisms do which?

Answer 3

Internal and external. (Internal-land animals, external sea animals)

Question 4

How does external fertilization occur?

Answer 4

Gametes join together outside the body of the female

Question 5

How does internal fertilization occur?

Answer 5

Gametes join inside the body of the female

Question 6

How many eggs/zygotes does external fertilization make use of? Why?

Answer 6

Many/many

More likely to be damaged outside

Question 7

How many eggs/zygotes does internal fertilization make use of? Why?

Answer 7

Few/few,

Protected by the moist internal environment of the female

Question 8

What are chromosome mutations?

Answer 8

When changes occur (this is abnormal) and causing variation in the number of chromosomes (not 46)

Question 9

What is a trisomy?

Answer 9

3 copies of a single chromosome (2n+1)

Question 10

What does down syndrome result from?

Answer 10

Trisomy of chromosome 21 (47, 21+)

Question 11

How common is down syndrome?

Answer 11

Average 3:1000 births, frequency increases w age of mother

Question 12

What are characteristics of down syndrome?

Answer 12

Short, w small, round heads and other facial features, mental disabilities, with IQ seldom above 70, shorter life expectancy (more likely to have respiratory disease and heart defects)

Question 13

What is Klinefelter syndrome?

Answer 13

Males with a trisomy of sex chromosomes (extra X chromosome)

Question 14

How common is Klinefelter Syndrome?

Answer 14

1:500 male births

Question 15

Characteristics of Klinefelter Syndrome?

Answer 15

Males, with male genitalia, but with underdeveloped testes that cannot produce sperm, and some female sexual development

Question 16

What female sexual development is possible in Klinefelter Syndrome?

Answer 16

Enlargement of breasts, less facial hair, higher voice

Question 17

What is a monosomy?

Answer 17

1 copy of a chromosome instead of two (2n-1)

Question 18

What is Turner Syndrome?

Answer 18

Females, with female external genitalia, but have a monosomy of the sex chromosomes, only have one X-chromosome

Question 19

How common is Turner syndrome?

Answer 19

1 to 3000 female births

Question 20

What are symptoms of turner syndrome?

Answer 20

Female external genitalia but underdeveloped ovaries and other abnormalities, such as webbed neck, abnormally short, broad chest

Question 21

What is parthenogenesis?

Answer 21

Development of an egg cell into a mature organism without being fertilized by sperm cell

Question 22

Given example parthenogenesis

Answer 22

Production of male bees

Question 23

What are the steps of normal embryo formation

Answer 23

Fertilization, cleavage, and gastrulation

Question 24

What is cleavage in a zygote?

Answer 24

Zygote divides many times by mitosis, forming a hollow ball with a single layer of cells called a blastula

Question 25

What is a blastula?

Answer 25

A hollow ball with a single layer of cells formed by multiple mitosis of zygote. There is no increase in size

Question 26

What is gastrulation in a blastula

Answer 26

One side of the blastula becomes indented, forming a gastrula

Question 27

What is a gastrula?

Answer 27

The product of gastrulation

Question 28

What are the three layers of a gastrula called?

Answer 28

The outer layer is called ectoderm, inner layer is called endoderm, middle layer is called mesoderm

Question 29

What is differentiation?

Answer 29

Cells of the three layers of the gastrula differentiate, or change into various tissues and organs of the animal

Question 30

What is growth?

Answer 30

Increase in number and size of cells

Question 31

What is fertilization?

Answer 31

Union of haploid sperm nucleus w haploid egg nucleus