Reproduction Review

Answer Key

http://pinktentacle.com/2009/01/tiny-doll-made-of-living-cells/

1. Define the following terms: Mitosis and Meiosis

Mitosis: The scientific term for cell division. Creates two genetically identical cells. Creates your body cells. Only one division.

Meiosis: Another form of cell division. Creates sex cells. Crossing over occurs to ensure all cells are genetically different. Creates 4 new cells. Two divisions.

2. Define the following terms and provide an example for each.

Asexual Reproduction: An organism generates offspring with

identical characteristics to itself since there is only one parent from which gets its genetic info. Depends on forms of Mitosis.

Examples: ANY of the following: Vegetative Propagation:

When a new organism is created from the roots, stems or leaves of plants

Examples: African Violet or Spider plant Regeneration:

When an organism is divided in fragments, it becomes a new organism by regenerating the missing parts.

Example: Planarian worm, Starfish

Sporulation: Spores are produced inside a

case until the mould matures. When the case ruptures, thousands of spores are released.

Example: Bread Mould Budding:

A tiny bud begins to form on the cell wall. The bud grows larger and eventually falls off.

Example: Yeast Binary Fission:

How bacteria grow. They multiply very quickly and can produce hundreds of thousands within a matter of hours.

3. What does PMAT stand for? Draw an image for each stage.

PMAT: The stages of Mitosis. Prophase, Metaphase, Anaphase, Telophase. Cytokinesis is the splitting of the cytoplasm between the two

cells at the very end of mitosis.

4. What is an organelle? Explain the functions of the following organelles:

1. Organelle Specialized structures in cells that

perform specific functions.2. Nucleus

The brain of the cell. Controls all cell functions.

3. Nucleolus The dark centre of the nucleus.

Makes ribosome parts.4. Cell membrane

The outer boundary of the cell. Controls what comes in and what goes out.

5. Cell Wall Only in plant cells. The rigid outer

layer which prevents loss of water and keeps the cell structure.

6. Chloroplast Only in plant cells. The

green pigmented parts which allow for photosynthesis to occur.

7. Endoplasmic reticulum The “canals” which

transport materials throughout the cell.

8. Vacuole Fluid filled sac containing

water, waste and nutrients.

9. Mitochondria The cell’s energy source.

Transforms nutrients into energy.

5. List two things a cell does during the cell cycle other than mitosis (cell division).

Grows Replicates DNA These occur during INTERPHASE which

happens before the actual division of the cell.

6. What is spontaneous generation? Give three examples of spontaneous generation.

The belief that cells magically appeared. Some examples: Mice from dirty clothes/corn husks. Maggots from rotting meat. Fruit flies from bananas.

7. How long does it take to complete the cell cycle? How long does the process of Mitosis take? In what phase does

the cell spend most of its time?

The cell cycle takes a total of 20 hours. Interphase takes up 18 hours of that time. This leaves 2 hours for the actual division

(Mitosis).

8. Give 4 examples of Mitosis occurring in everyday life.

1. A cut healing.2. Any of your body cells regenerating.3. Grass growing.4. A worm / lizard growing back its tail.5. A starfish growing back its arm.6. Bacteria reproducing and making you sick.7. Yeast making bread rise.8. Etc.

9. What are the six functions all cells need to do in order to survive?

1) Eat and use energy2) Store info and control functions3) Detect and respond to changes in the

environment4) Eliminate waste5) Build and repair parts6) Reproduce

10. What does DNA stand for? (Know how to spell it correctly!)

Deoxyribonucleic Acid• Practice this several times• Come up with tricks to

remember it

11. How many chromosomes are in body cells? How many are in sex cells? Why do these numbers differ?

We have 46 chromosomes in each body cell. There are 23 chromosomes in each sex cell. These numbers are different because each fully

developed / mature cell needs to have 46 chromosomes. Our sex cells (sperm and egg) have only 23 chromosomes

because they need to join together to form a new human being; They have half of the required genetic information to make a new person.

If our sex cells had 46 chromosomes, then when they combined they would create a baby with 92 chromosomes which would cause all sorts of problems!

12. What are the three laws or premises of the Cell Theory?

1) All living organisms are composed of one or more cells.

2) Cells are the basic units of structure and function in all organisms.

3) All cells come from already existing cells.

13. What is Cancer?

Cells dividing uncontrollably, going through Mitosis (dividing) at a fast rate.

Causes: smoking, sun, radiation, air quality (pollution), genetic factors.

Pre-Test Questions Matching

________ A planarian (worm) is cut in two and grows back with two heads.

________ A sandwich is left in your locker all year and is covered in mould.

________ In bread making, the bread starts to rise because of the yeast reproducing.

________ You pick up a bacteria, and by lunch there are 20,000!

________ From one spider plant, you end up with ten identical plants.

A

A. Binary FissionB. SporulationC. BuddingD. RegenerationE. Vegetative Propagation

B

C

D

E

Identify the following cell types

Bone cell Red Blood cell

Nerve cell Muscle cell

Genetics Pre-test

1. A newly fertilized egg is called a: Zygote

2. A cell spends most of its time in which part of the cell cycle? Interphase

3. Which of the following are examples of gametes? Buds and Spores Sperm and Egg Moulds and Yeast Zygote and Embryo

4. A sex cell has: A haploid number of chromosomes, 23. A haploid number of chromosomes, 46. A diploid number of chromosomes, 23. A diploid number of chromosomes, 46.

5. Monozygotic twins that are formed from one original zygote are also called:

Identical Twins

6. The most critical period of embryonic and fetal development is: The first trimester (0-3 months). The second trimester (3-6 months). The third trimester (6-9 months). After the baby is born.

7. A heterozygous or hybrid individual for eye colour would have the following genotype. Bb BB Brown eyes Blue eyes

8. Brown hair is dominant over blonde hair. A homozygous recessive individual for hair colour would have the following phenotype: Blonde Hair

9. If a homozygous dominant dad with curly hair and a homozygous recessive mom for straight hair have kids, all the kids will have the following genotypes: CC Cc CC or cc cc

10. Twins that are attached in the uterus are called: Conjoined Twins

Dad: CC mom: ccCc Cc

Cc Cc

C C

c

c

Part B: True and False: Correct all the false statements True 1. Sex cells must have a haploid (1N) number of chromosomes.False 2. Alcohol and caffeine will never affect a baby’s development.

Alcohol and caffeine WILL affect a baby’s development.

True 3. If two parents were to have 100 babies, if no twins were born, each baby would be genetically different.

True 4. BB is describing a homozygous trait.False 5. A baby boy will inherit more traits from his dad than from his mom.

Any baby inherits traits combined randomly from each parent because of crossing over.

True 6. Gametes (sperm and egg) come together to form a zygote.False 7. bb is describing a homozygous dominant trait.

homozygous recessiveFalse 8. Conjoined twins are more frequently found among males.

femalesTrue 9. Humans have 23 chromosome pairs.True10. The dominant trait is always expressed.

Part C: Matching: 1. The trait that is not expressed.

D. Recessive

2. The physical or observable trait. Ex. Brown eyes E. Phenotype

3. The individual has two different genes for a given trait but the DOMINANT one is displayed.

A. Heterozygous

4. During Meiosis, the parent’s gene pairs are separated into sperm and eggs.

B. Gametes

5. A piece of DNA that codes for specific traits. C. Gene

Part D: Short and Long Answer  1. What are the two types of twins? How are they formed differently during

fertilization? (3 marks)

 Monozygotic and dizygotic. Monozygotic twins are formed when one sperm fertilizes one egg and the egg splits into two. Dizygotic twins are formed when two sperm fertilize two separate eggs making two babies at the same time.

 2. Red roses are dominant over white roses. If a heterozygous rose is crossed with a

white one, what will be the genotypes and phenotypes of the offspring? (4 marks) Parents: Rr x rrGenotype: 50 % Rr 50% rrPhenotype: 50% Red roses, 50% white roses    

rR

r

r

Rr rr

Rr rr

3. In humans, the ability to roll your tongue is a dominant trait. If a father is homozygous dominant for this condition (RR) and the mother is recessive (rr), what percentage of their children will be able to roll their tongues? Explain your answer by showing all of your work. (4 marks)

Parents: RR x rrGenotype: 100% RrPhenotype: 100% Roll tongue

All (100%) of their children will be able to roll their tongues.

RR

r

r

Rr Rr

Rr Rr