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Mahopac Central School
District Curriculum 2003-04
Reproduction and Development
A. The biosphere is the community of plants and animals on the Earth
1. The cell theory applies to all living things and says that:
a. living things are composed of cells
b. cells are the basic unit of structure and function of living things
c. all cells come from other cells
2. The cell theory has at least one exception
a. viruses may be considered alive but they lack the typical cell structures
B. Cell Structures – the parts are known as organelles
1. Cell Membrane – it surrounds the cell and controls what enters and leaves
2. Cytoplasm – the watery material that contains organelles and makes up most of
the cell
a. it is found between the nucleus and the cell membrane
3. Nucleus – the information center for the cell
a. it is found in all cells
b. it contains the chromosomes
4. Chromosomes – they contain most of the genes of a cell which are composed of
DNA, the chemical that directs heredity
5. Mitochondria – the cite of cellular respiration where food is used to produce
energy
6. Ribosomes – they assist in building proteins
7. Vacuoles – are storage for both nutrients and waste
8. Lysosomes – (animal cells only) – they contain enzymes that break down protein
9. Cell Wall – (plant cells only) an outer shell that protects and supports plant cells
10. Chloroplasts – (plant cells only) they contain chlorophyll, a substance that can
change light energy into chemical energy (food) for the cell
11. In order for cells to survive they must take in nutrients (through the cell
membrane) which are converted to energy (in the mitochondria) or used to make
materials that the cell or organism needs
C. Unicellular versus Multicellular
1. Organisms that consist of just one cell are called unicellular
a. amoeba, bacteria, paramecium, euglena, and diatoms are all examples
2. Organisms that are multicellular consist of many cells
a. in these organisms the cells need to specialize (do fewer jobs and usually do
them better)
b. a multicellular organism has many individual specialized cells that work
together, interdependently, so that the organism can function at a higher level
of complexity than one cell living alone
c. the form a tissue takes commonly reflects its function – fins, flippers, wings
are beautifully adapted to their use (form follows function)
D. Levels of Organization
1. In general, in multicellular organisms, the levels are: cells, tissues, organs, organ
systems, and organisms
2. Different cells perform different tasks, they specialize
3. A tissue is a group of cells that perform the same function
a. tissues are used to cover the body, connect other tissues and organs
together, move parts of the body, carry messages to and from parts of the
body, store nutrients, and do other jobs
Mahopac Central School
District Curriculum 2003-04
4. An organ is a group of tissues that work together to perform a certain function
5. An organ system is a group of organs that work together to perform specific
functions
6. An organism is the final product of the levels of organization – it’s the living being
E. Plants as organisms
1. Like all living things plants consist of tissues and organs
2. These groups of tissue include roots, stems, and leaves
3. Roots
a. they anchor the plant to the ground
b. they store nutrients
c. they absorb water and minerals from the soil
d. they transport water and minerals to the stems which carry them to the leaves
4. Stems
a. they support the plant and hold the leaves up
b. they store food
c. they transport nutrients, minerals, and water between the roots and the
leaves
5. Leaves
a. they are the site of photosynthesis
b. photosynthesis – light energy is converted into chemical energy during which
oxygen and sugar are produced
F. Classification of Life
1. All living things are related to one another
2. Linnaeus developed a classification system called binomial nomenclature
a. it assigns a two-word Latin name to each organism
b. the system is based on whether the organisms share the same
characteristics, structures, and origins
3. Kingdom, Phylum, Class, Order, Family, Genus, Species is the order
a. kingdom is the broadest, most general category while species is the smallest,
most specific group
4. There are five kingdoms of life on Earth:
a. Moneran – bacteria
b. Protist – protozoa and algae
c. Fungus – molds, yeast, and mushrooms
d. Plant – seed plants, cone bearing plants, and ferns
e. Animal – insects, fish, reptiles, birds, and mammals
G. Human Organ Systems
1. Humans have systems for: digestion, respiration, reproduction, circulation,
excretion, control and coordination (nervous and endocrine systems), movement
(muscular and skeletal systems), and protection from disease (immune system)
2. These systems interact to form a whole organism
3. The digestive system – for the mechanical (chewing and churning) and chemical
(enzymes) breakdown of food
a. this system is necessary so that food can be absorbed into the body and
transported to all the cells
b. the parts include: teeth (mechanical digestion), esophagus, stomach
(mechanical and chemical digestion), small intestine (absorption of nutrients),
large intestine (storage of undigested waste), digestive glands (salivary),
pancreas, liver, and gall bladder
Mahopac Central School
District Curriculum 2003-04
4.
5.
6.
7.
8.
9.
1) these last three secrete chemicals like bile and enzymes that aid in
chemical digestion
The respiratory system – to carry out gas exchanges – it supplies oxygen and
removes carbon dioxide
a. this system is necessary so that cells can use the oxygen to release energy
that is stored in food
b. the parts include: nose, trachea, bronchi (direct air to the lungs), alveoli,
capillaries (gather oxygen), lungs (carbon dioxide expelled), diaphragm
(muscles that help inflate and deflate the lungs)
The circulatory system – it moves substances to and from the cells
a. this system is necessary to supply needed materials to cells and remove cell
products and cell wastes
b. the parts include: heart (a pump), lymph vessels (return of tissue fluids to the
bloodstream), lymph fluid (fluid between spaces in tissues), arteries (carry
blood and oxygen from the heart), veins (carry blood and wastes back to the
heart), capillaries (gather wastes released by cells), blood (circulating fluid
containing platelets, metabolic wastes, and specialized cells).
The excretory system – it gets rid of all body waste products and removes
excess heat energy
a. this system is necessary because the build up of waste products poisons
cells
b. the parts include: lungs (releases CO2), skin (sweat glands), kidneys (filter
blood), urinary structures (release liquid wastes), large intestines (release
solid wastes), and circulatory system (move waste to the appropriate organ)
The muscular/skeletal system – it provides support and protection for organs and
produces blood cells (in the bone marrow)
a. this system is necessary because movement is required to escape danger,
obtain food and shelter, and to reproduce
b. the muscles move the skeleton, line the blood vessels and the digestive tract,
and the heart pumps blood
c. the parts include: bones and muscles (voluntary – under conscious control),
(involuntary/smooth – not under conscious control), (cardiac – heart)
d. the nervous system coordinates movement
The nervous and endocrine systems – they interact to control and coordinate the
bodies response to internal and external changes – respond to stimuli
a. this system is necessary to link all other systems together into a functioning
whole
b. the parts include: brain (central control), spinal chord (links the brain to other
parts of the body), nerves (pathway to muscles, glands, and sense organs),
glands (release powerful chemicals)
c. the endocrine system regulates growth, development, and reproduction
through glands
1) these glands produce hormones – powerful chemicals that affect other
parts of the body
d. the production of sweat is a bodies response to stressful stimuli
The immune system – it protects the body from infectious diseases
a. this system is necessary because it produces cells and molecules that
identify and destroy microbes that enter the body – prevents diseases
1) a disease is a breakdown in the structure or function of an organism
Mahopac Central School
District Curriculum 2003-04
2) cancer is a general name for diseases caused by unregulated cell growth
– it is caused by a change in the genes that regulate cell growth
b. the parts include: specialized cells (white blood cells), and molecules
(antibodies)
10. The reproductive system – it produces the sex cells necessary for the production
of offspring
a. Human Female – produces female sex cells (eggs) in the ovaries
1) usually one egg is produced every 28 days
2) the egg travels to the uterus through the fallopian tubes
3) if fertilization occurs after the male sex cells are deposited in the vagina,
the egg attaches to the uterine lining
4) if fertilization doesn’t occur, the egg and the uterine lining pass out
through the vagina via menstruation
b. Human Male – produces male sex cells (sperm) in the testes
1) sperm cells are produced all the time, not just once a month
2) small tubes (sperm ducts) carry the sperm to the penis
3) prostate and seminal glands add secretions to the sperm cells
4) the penis transfers the sperm cells to the vagina – otherwise the body
reabsorbs them
H. Heredity – the passing of genes from parent to offspring
1. The chromosomes of cells are composed of a molecule of DNA – it looks a bit
like a twisted ladder
2. The rungs of the ladder are made up of pairs of substances called bases
3. The order of the bases are thought to provide the hereditary code because their
order directs the production of proteins that make up the organism
4. The DNA molecule codes and stores genetic information, its function is to direct
the cell on how to carry out life processes
a. each unit of information that contains the code for a particular trait
(characteristic) is called a gene
5. Chromosomes come in pairs
a. each pair of chromosomes has the gene for a particular trait in the same
position along its structure
b. it is a pair of genes that determine the trait of an organism
c. a single trait may be the result of one pair of genes or by many pairs of genes
6. When organisms reproduce, genetic instructions are passed from one generation
to the next
7. There are two types of reproduction: asexual and sexual
I. Asexual Reproduction – the creation of a new individual without the joining of two
cells
1. All genes given to the offspring come from one parent
a. therefore, the offspring is genetically identical to the parent
2. Types of asexual reproduction include:
a. fission – the splitting of a one cell organism into two equal halves
1) an amoeba is an example
b. budding – the splitting of a one cell organism into two portions with equal
genetics but unequal cell materials
1) yeast is an example
c. runners – a slender branch which takes root near its tip
1) a strawberry plant is an example
d. bud – a protuberance which is capable of developing into a new organism
Mahopac Central School
District Curriculum 2003-04
1) a potato bud (usually called eyes)
e. cutting – a part of a plant removed for vegetative propagation
1) bamboo is an example
f. grafting – attaching a portion of one plant into another so that a permanent
union is formed
1) multiple apple varieties on one tree, for example
g. spores – one or a few cells capable of giving rise to a new individual
1) bread mold is an example
h. bulbs – a single globose bud, generally subterranean, and usually layered
1) onions, lilies, and tulips are examples
i. rhizomes – a root like stem that grows on or under the ground producing
stems and roots
1) lawn grass is an example
3. Asexual reproduction involves mitosis
Phase one – chromosomes in the nucleus become visible
Phase two – chromosomes unwind and unzip – they duplicate so they are
doubled and in identical pairs
Phase three – chromosomes shorten and thicken while the nuclear membrane
disappears
Phase four – duplicated chromosome pairs line up in the center of the cell and
split. One chromosome from each pair moves to the outside of the cell
Phase five – chromosomes regroup and a new nuclear membrane forms around
each group
Phase six – the cell splits in half – there are now 2 identical versions (called
daughter cells) of the original cell
4. In multicellular organisms, the new cells allow for growth, maintenance and repair
of body cells
J. Sexual Reproduction – the joining of two cells to begin the development of a new
individual
1. Half the DNA comes from each of the two parents
2. Special cells called sex cells contain only half of the genetic information
a. sex cells contain one chromosome from each pair of chromosomes
b. male sex cells are called sperm cells (pollen cells in plants), while female sex
cells are called egg cells
3. Sex cells are created by meiosis
Phase one – chromosomes in the nucleus become visible
Phase two – chromosomes unwind and unzip – they duplicate as they are
doubled in identical pairs
Phase three – chromosomes shorten and thicken while the nuclear membrane
disappears
Phase four – duplicated chromosome pairs line up in the center of the cell – the
cell divides so that each cell has two sets of genes from one side of the original
chromosome pair
Phase five – the duplicated chromosomes line up in the center of the cell and
split – one chromosome from each pair moves to the outside of the cell
Phase six – chromosomes regroup and a new nuclear membrane is formed
around them
Phase seven – the cell itself splits in half into two sex cells (the DNA was not
duplicated)
Mahopac Central School
District Curriculum 2003-04
4. One original cell forms four sex cells – each with half the number of original
chromosomes
a. in cells that are not sex cells strands of DNA come in pairs – sex cells have
only one strand of each pair
5. For a new organism to be complete a male sex cell and a female sex cell must
unite
a. this joining of sex cells is called fertilization
b. a fertilized egg is called a zygote and contains a full set of genetic information
c. fertilization in some animal species takes place outside the body – this is
called external fertilization
1) salmon and frogs are examples
d. fertilization is some animal species takes place inside the body – this is called
internal fertilization
1) birds, snakes, dogs and people are examples
6. In humans, the fertilized egg (called an embryo) undergoes many cell divisions
a. eventually, three layers of cells develop
b. these three layers produce cells which are different from each of the other
layers
c. they will become different tissues, organs, and organ systems
7. In humans, all organs begin to develop by three months and body features
develop by six months
a. during the last three months, organs and features develop so that they can
function after birth
8. As humans grow from infant to adult, their bodies change
a. body structures and functions change as organisms age
9. Plant reproduction
a. flowers contain reproductive parts called pistils and stamens
1) the pistil is the female reproductive organ and the stamen is the male
reproductive organ
b. pollination leads to the fertilizing in flowers of a female cell by a male cell
1) the final result is a zygote that develops into a seed
2) a seed is a young plant surrounded by stored food and covered with a
protective coat
c. not all plants develop in the same way – some, like ferns and mosses
develop spores
1) the spores develop a plant-like structure that does not resemble the
parent
2) that structure produces eggs and sperm that after fertilization grow into
the leafy parent plant we call a fern
K. Not all animals develop in the same way, either
1. Some insects have a four stage life history called complete metamorphosis
2. The stages are: egg, larva, pupa, and adult
a. the larva that hatches from the egg does not look like the adult form – it’s
worm-like or caterpillar-like
1) this is the stage of eating and growing
2) the larva often doesn’t eat the same food that the adult eats
b. the larva forms a shell or case around itself and enters into the pupa stage
c. in the pupa, the insect changes into the adult form
3. Some amphibians also undergo complete metamorphosis
Mahopac Central School
District Curriculum 2003-04
a. frogs lay eggs and they’re fertilized outside the body of the female by the
male
b. the eggs hatch into tadpoles
1) this is the fish-like stage with fins and gills
c. the tadpole changes into a typical frog-like shape over time
4. Some insects have a three stage life history called incomplete metamorphosis
5. The three stages are: egg, nymph, and adult
a. the nymph that hatches from the egg looks very much like the adult
L. Heredity
1. Gregor Mendel proposed that various characteristics of plants are controlled by
factors that occur in pairs
a. today, we called these factors genes
2. Mendel called the trait (characteristic) that hid the other the dominant trait
3. He called the trait that was hidden and did not appear the recessive trait
a. when both genes of a pair for a particular trait are the same, the organism is
said to be pure for that trait
b. when an organism has different genes for a trait it is considered a hybrid
4. It turns out that not all genes are dominant or recessive
a. both genes of the pair for a trait can influence the trait in an individual
b. this is called incomplete dominance or blending
1) the offspring does not resemble either of its parents
5. To understand what kinds of offspring will occur, scientists use models of genetic
inheritance
a. these models can help to determine the probability or chance of a trait being
expressed (seen)
6. One such model is a Punnett Square
a. the gene pair from the female parent is put across the top of the grid
b. the gene pair from the male parent is written down the left side of the grid
c. each box represents 25% of all possible offspring
7. Another model is a pedigree chart
a. each level represents a new generation
b. males are represented as squares and females as circles