Meiosis Cycle

Question 1

is a special type of cell division
that creates gametes (sperm & egg) with
half the chromosome number.

Answer 1

Meiosis

Question 2

What is the purpose of Meiosis?

Answer 2

It ensures genetic diversity in offspring.

Question 3

Chromosome numbers:

Answer 3

● Somatic (body) cells: 46 chromosomes (23 pairs, diploid, 2n).
● Gametes (sperm & egg): 23 chromosomes (haploid, n).

Question 4

Why is meiosis important?

Answer 4

● Halves the chromosome number so fertilization restores the correct number (46).
● Mixes genetic material through crossing over & independent assortment.
● Prevents genetic overload (polyploidy), which is fatal in humans.

Question 5

Which phase of meiosis involves the condensation of chromosomes, pairing of homologous chromosomes, and crossing over, where homologous chromosomes exchange genetic material to create new gene combinations?

Answer 5

Meiosis 1: Prophase 1

Question 6

In which phase of meiosis do homologous pairs align randomly in the center of the cell, leading to independent assortment and increased genetic diversity?

Answer 6

Metaphase I

Question 7

In which phases of meiosis do homologous chromosomes separate into two haploid cells, with each cell having 23 chromosomes, but the sister chromatids still remain attached?

Answer 7

Anaphase I & Telophase I

Question 8

TRUE OR FALSE: Meiosis occurs in both sexes but follows different pathways after division.

Answer 8

TRUE

Question 9

TRUE OR FALSE: Sperm & oocytes are both haploid (23 chromosomes) but differ in size, structure,
and function.

Answer 9

TRUE

Question 10

What is the difference between gamete maturation In male and female?

Answer 10

Males: Start producing sperm at puberty and continue for life.
○ Females: Begin meiosis before birth but only complete it if fertilization occurs.

Question 11

Process of sperm cell development in the testes (seminiferous tubules).

Answer 11

Spermatogenesis

Question 12

Spermatogenesis begins with _____

Answer 12

A diploid spermatogonium (stem cell) that divides mitotically.

Question 13

TRUE OR FALSE: Some cells become sperm, others remain as stem cells for
ongoing sperm production.

Answer 13

TRUE

Question 14

In the steps of spermatogenesis, what step is the diploid stem cell that divides mitotically to maintain sperm production?

Answer 14

1. Spermatogonium (2n):

Question 15

In the steps of spermatogenesis, what step undergoes Meiosis I → divides into two haploid secondary spermatocytes
(n).

Answer 15

2. Primary Spermatocyte (2n):

Question 16

A step in spermatogenesis that undergo Meiosis II → produce four equal-sized spermatids (n).

Answer 16

3. Secondary Spermatocytes (n):

Question 17

During spermatogenesis, what happens to spermatids as they mature into spermatozoa?

Answer 17

4. Spermatids mature into Spermatozoa (Sperm):

Gain a flagellum (tail) for movement.

Mitochondria in the midpiece provide energy (ATP) for swimming.

Acrosome (head region) contains enzymes to penetrate the oocyte.

Question 18

Structure of a Mature Sperm Cell

Answer 18

Head, Midpiece, Tail (Flagellum)

Question 19

What structures in sperm contain genetic material and assist in penetrating the oocyte?

Answer 19

Sperm Head

Question 20

Enzyme-filled cap that helps sperm penetrate the oocyte.

Answer 20

Acrosome

Question 21

Packed with mitochondria to produce energy for swimming.

Answer 21

Midpiece

Question 22

Enables movement toward the oocyte.

Answer 22

Tail (Flagellum)

Question 23

TRUE OR FALSE: Males produce billions of sperm over their lifetime.

Answer 23

FALSE

trillions

Question 24

TRUE OR FALSE: Damaged spermatogonia (due to toxins) will mature into sperm.

Answer 24

FALSE

will not mature

Question 25

TRUE OR FALSE: Toxic exposure to mature sperm may impair their swimming ability, preventing fertilization.

Answer 25

TRUE

Question 26

Meiosis II (Equational Division, 23 → 23 chromosomes):

Answer 26

4. Prophase II: Chromosomes condense again. 5. Metaphase II: Chromosomes align in the center. 6. Anaphase II: Sister chromatids separate and move to opposite poles. 7. Telophase II: Four genetically unique haploid gametes (sperm or eggs) form.

Question 27

New combinations of genes from both parents.

Answer 27

Crossing over (Prophase I):

Question 28

What process in meiosis results in the random alignment of chromosomes, leading to trillions of possible gene combinations?

Answer 28

Independent assortment.

Question 29

TRUE OR FALSE: Without mitosis, fertilization would double chromosome numbers, leading to genetic disorders.

Answer 29

FALSE: MEIOSIS

Question 30

TRUE OR FALSE: Crossing over & independent assortment make each person unique.

Answer 30

TRUE

Question 31

is the process of egg (oocyte) formation in females.

Answer 31

Oogenesis

Question 32

A stage of oogenesis: What is the process that begins with a diploid oogonium (2n), which grows, undergoes DNA replication, and becomes a primary oocyte (2n), starting meiosis but halting at Prophase I before birth?

Answer 32

Before Birth

Question 33

At puberty, how many oocytes remain, and what happens each month in response to hormones

Answer 33

Around 400,000 oocytes remain, and each month, one or more oocytes resume meiosis in response to hormones.

Question 34

During the completion of Meiosis I, what happens to the oocyte and the first polar body?

Answer 34

Meiosis I completes, dividing into two uneven haploid cells: The secondary oocyte (large, n) continues development. The first polar body (small, n) usually degenerates.

Question 35

What happens during ovulation in the mid-menstrual cycle, and what is the status of meiosis at this time?

Answer 35

The secondary oocyte is released into the uterine (fallopian) tube, and meiosis halts again at Metaphase II until fertilization occurs.

Question 36

What happens if fertilization occurs, and what are the outcomes of Meiosis II?

Answer 36

If fertilization occurs, Meiosis II completes, producing: The ovum (mature egg, n) with all the cytoplasm. The second polar body (n), which degenerates. Then, the nucleus of the sperm merges with the ovum, fertilization occurs, and a zygote (2n) is formed.