Biology

Characteristics of Organisms

- All organisms are made up of one or more cells

- Energy
 From food
 From cellular respiration, a process that breaks down substances from food and produces
energy and waste products.
 Heterotroph (an organism that cannot make its own food and relies on other sources):
 Cells use glucose, a type of sugar to create energy
(glucose + oxygen -> carbon dioxide (waste) + water + energy)
 Autotroph (organisms that can make their own food):
 Plant cells collect light energy to use for photosynthesis
(carbon dioxide +water + light energy -> oxygen +glucose)

- Respiration, or exchange of gases

 Animals replenishes oxygen and removes carbon dioxide
 Plants replenishes carbon dioxide and removes oxygen

- Excretion
 Getting rid of waste, or feces

- Reproduction
 Unicellular organisms through cell division
 Multi-cellular organisms reproduce when two parents contribute reproductive cells that will join
to form a new individual

- Growth and Development

 Growth – an increase in size and mass of a particular organism over a period of time
 Development – a process wherein a particular organisms transforms itself from a lone cell into a
more complicated multi-cellular organisms

- Ability to respond to their environment

 A response is any behavior of a living thing that results from an internal or external stimulus
>Internal stimulus: something inside of a living thing which causes a response in that living thing
or in one of its body parts,
>External stimulus: something outside of a living thing which causes a response in that living
thing or in one of its body parts.
Life Cycles

Metamorphosis – in which insects develop, grow, and change over time

1) Incomplete metamorphosis – the mode of development of certain insects that includes three distinct
stages: the egg, nymph, and the adult stage

Examples: grasshoppers, crickets, dragonflies, earwigs, stinkbugs, praying mantises,

cockroaches, etc.

Female insects lay eggs, which are covered by an egg case

Eggs hatch into nymphs, which look like small adults, but wingless – nymphs eat the same food and
live in the same habitat as adults, they mold outer casings several times

Nymphs reach adult size and grow wings – they stop molting at this stage

2) Complete Metamorphosis – the mode of development of certain insects that includes four distinct
stages: the egg, larva, pupa, and imago

Examples: Butterflies, moths, bees, wasps, ants, flies, beetles, etc.

Female insects lay eggs

Larvae hatch from the eggs, usually have worm-like shape with six legs – molt their skin several times

Larvae make a hard, protective case around themselves where they develop into their adult form with
wings, legs, internal organs, and other parts

Larvae change into adults inside their protective case and breaks out of them

Human Life Cycle

Fertilization, where a sperm and an egg form to make a one-celled individual that will grow and
develop for about nine months

Baby – 0 to 2 years old

Child – 3 to 12 years old

Teenager – 13 to 18

Adult, who is capable of producing reproductive cells through the process of meiosis

Elderly person, who can live up to an average of 78 years

Flower Life Cycle

Seed

Germination/Sprouting – the process by which the seed grows to form leaves or buds. Seeds wait to
germinate until three needs are met: water, correct temperature (Warmth), and a good location

Growth – the process of photosynthesis

Reproduction – the female part of the flower is called the pistil and it has four parts—the stigma, style,
ovary, and ovules. The male part of the flower is called the stamen which consists of the filament and
the anther, where pollen is made.

 Stigma = to catch pollen- sticky or hairy

 Style = transports the pollen into the ovary
 Ovary = where eggs are fertilized and becomes seeds (in fruit-producing plants, the ovary ripens
and becomes fruit)
 Ovule = develops into seeds when fertilized

 Anther = produces pollen

 Filament = supports the anther

Pollination – when the male and female structures are further apart, plants depend on insects, birds,
animals, wind, water, or other pollinators to carry polled from the male flowers to the female flowers.
Brightly colored petals, strong smell, nectar, and pollen attract pollinators.

Seed Spreading/Dispersal – when seed are spread in many ways

Stimuli and Behavior

Response: any behavior of a living thing that results from an internal or external stimulus

Types of responses and behaviors:

a) Instinctive behavior: natural response; especially a fight or flight response, based in a need to
protect themselves from danger
(e.g. horse perceives danger and will run or fight)

b) Learned behavior: response based on experience

(e.g. a dog fetching a ball when its owner throws)

c) Voluntary response: a behavior of a living thing that is under conscious control; doesn’t
automatically happen
(e.g. drinking water when thirsty)

d) Involuntary response: a behavior of a living thing that is not under conscious control
(e.g. sweating)
Hemeostasis of Organisms and Feedback

A primary goal for an organism’s response to both an internal and external stimuli is to maintain a
relatively constant internal environment; homeostasis. Factors of homeostasis include the concentration
of ions and glucose, pH levels, and temperature.

Disturbing factor

Stimulus

Sensor—constantly monitors conditions—nerve cells

Integrating center—contains the set point (the normal range for a condition), and compares it to actual
conditions—a particular part of the brain, spinal cord, or endocrine gland cells

Effector—causes changes to make up for the difference from the set point response, and returns the
condition to set point—glands or muscles

Response

Negative feedback loops—act to oppose the stimulus that triggers them:

 One is activated when a parameter—like body temperature—is above the set point and is
designed to bring it back down
 One is activated when the parameter is below the set point and is designed to bring it back up

Positive feedback loops— amplify the starting signal, and only happens in some biological cases, like
childbirth.
Cells

Cell Theory

1—all living things are made up of one or more cells

 Unicellular: made up of one cell—e.g. bacteria, protists

 Multicellular: made up of many cells—e.g. plants, animals

2—all cells come from pre-existing cells (cells divide to make more cells)

3—cells are the basic unit of life:

- Cells are organized in a way that benefits the organism as a whole:

Cells -> Tissues -> Organs -> Organ systems

- Cells get energy from food and removes waste

- Cells are also involved in growth:
 Unicellular organism = growth in cell size
 Multicellular organism = increase in cell number

Prokaryotic and Eukaryotic Cells

 Eukaryotic cell: has a membrane-enclosed nucleus that stores genetic information and provides
instructions in the DNA—e.g. plants, animals, fungi
 Prokaryotic: do not contain a membrane-enclosed nucleus—e.g. bacterium, archaea
o DNA: a molecule located in chromosomes, provides specific guidelines about traits inherited
from parents
Cell Structure

Cell membrane:

- Forms the outer surface of the cell

- Controls what materials move into and out of the cell

Cytoplasm:

- Fluid that fills the cell

- Transports materials and allows them to move around
- Contains organelles

Mitochondria: (prokaryotic cells do not have them)

- Powerhouse of the cells

- Provides energy for the cells
- Converts glucose (food for the cells) and oxygen into carbon dioxide, water, and energy in the
form of ATP

Eukaryotic Prokaryotic

Cytoplasm

Cytoplasm Cell membrane

Cell membrane

Mitochondria
Plant vs. Animal Cells

Plant cells have cell walls while animal cells don’t:

 located outside the cell membrane

 made up mostly of cellulose
 gives shape to celll protets cell from infection
 non-plant organisms that have cell walls: bacteria, fungi, and algae

Plant cells have chloroplasts to perform photosynthesis while animals don’t:

 contains chloropyhll: several green pigments found in green plants to give off green color
 captures light energy to make sugar through photosynthesis

Plant cells have one large vacuole while animals cells only have a few small ones:

 surrounded by a membrane
 filled with a watery fluid that is filled with materials such as nutrients and waste products stored
in fluids
 helps regulate turgar pressure, which is the pressure placed on the plant cell wall by water
passing in and out of the cell
Photosynthesis

Photosynthesis is a process in which it collects sunlight, water, and carbon dioxide to produce glucose,
energy for a plant, and oxygen, the waste product. Photosynthesis primarily happens in the leaves,

Sunlight (radiant energy) Water (H2O) Carbon dioxide

Collected by chlorophyll Hydrogen through stomata

Used to convert

Glucose (food) Oxygen (waste product)

Cellular Respiration

Cellular respiration is the process that the cells of organisms perform in order to get energy. Glucose is
used through mitochondria to make ATP, energy for the cells.

Types of cellular respiration:

 Aerobic respiration = oxygen is used

Glucose + Oxygen Carbon dioxide + Water + Energy stored in ATP

 Anaerobic respiration = oxygen is not used

Lactic acid fermentaion + glucose Energy

Alcoholic respiration converts glucose to produce carbon dioxide

Some organism:

- Only use aerobic respiration

- Only use anaerobic respiration
- Use both
Homeostasis in Cells

Homeostasis: maintenance of a consistent internal environment

Cells need to extract energy in order to maintain homeostasis. Nutrients that pass into cells are used to
provide this energy .

Energy is needed for:

- Making materials
- Cell growth
- Cell division
- Cell production

Homeostasis processes in cells:

1) Reproducing

Cells divide for 3 purposes:

 Growth
 Replacement
 Repair

2) Extracting energy from food

Sugar molecules get absorbed into wall of small intestine, then move into tiny blood vessels and are
carried away to cells of the body. Enzymes break down the nutrients.

3) Getting rid of wastes

Cellular respiration results in wastes like carbon dioxide, that needs to be gotten rid of through the lungs,
and water, that needs to be gotten rid of as urine through the liver.

4) Transporting materials through diffusion and osmosis

Diffusion— movement of nutrients, ions or small molecules, through the cell membrane from an area of
higher concentration to an area of lower concentration

Osmosis— movement of water through the cell membrane, usually from the side of the weaker
concentration to the side of the stronger concentration.

Hypertonic solution: has greater concentration of solute than another solution

Hypotonic solution: has lower concentration of solute than another solution

Isotonic solution: has the same solute concentration as another solution.

Unicellular Organisms

Unicellular locomotions

 Cilia—hair-like projections on a cell that can whip back and forth to move the cell
 Flagella—skinny tails on some unicellular organisms that allow them to move by whipping the
extensions back anf forth
 Pseudopod— a temporary extension of the protoplasm (the cytoplasm and the nucleus) used
for moving around

Unicellular reproduction

- Asexual reproduction

Binary fission—A reproductive process commonly used by unicellular organisms, which a cell splits to
form two separate cells

- Sexual reproductiom

Conjugation—A temporary connection only between two unicellular organisms of the same species that
transfer genetic material to each other

Ingestion

Endocytosis: the movement of materials such as food into the cytoplasm of a cell through membranous
vesicles or vacuoles

1) Phagocytosis: when an organism engulfs a material

2) Pinocytosis: when an organism gulps a droplet of fluid

Elimination

Exocytosis: the movement of waste materials out of the cytoplasm of a cell through membranous
vesicles or vacuoles
Ecology

1- Biomes

Biome: a type of environment in which organisms can be found; each supports different organisms that
are adapted to that region

Terrestrial Biomes

Type of Biome Area Features Climate Organisms

Dry biome Caparrals > Mountain slopes > Long, hot, dry > Small trees
> Rocky hills summers > Shrubs
> Flat plains > Short, mild, rainy > Brush Rabbits
winters > Coyotes
Dry biome Deserts Flat and dry > Less than 30 cm > Cacti
of annual rainfall > Mice
> All rain that falls > Bobcats
each year
evaporates
> Cold
> Hot and dry
Grassland (prairie) Tropical savannas Grasslands with > Long dry season > Trees like
scattered trees > Short wet eucalyptus trees
season > Koalas
> Dingoes
Grassland (prairie) Temperate Grasslands > Seasonal > Grazing by large
grasslands without woody drought mammals
shrubs and trees > Occasional fires > Pampas grasses
> Rheas
Forest Tropical seasonal Densely growing > 20-25 C > Mosses
forests trees that lose > Dry in winter > Rhinos
their leaves during > Rain in summer > Tigers
short dry seasons
Forest Temperate In mid-latitude Go through all 4 > Broadleaf trees
deciduous forests areas with lots of seasons; summer, > Cardinals
trees that change winter, autumn, > Porcupines
colors and lose fall
leaves
Forest Tropical Tall trees with Year-round > Golden lion
rainforests noticeable vertical warmth tamarins
layers > Boa constrictor
Forest Temperate Coniferous or > High humidity > Predominant
rainforests broadleef forests > Less annual coniferous trees
precipitation than > Beaver
tropical > Cougar
> Lower average
temperatures than
tropical
Forest Taigas (boreal or Dominated by > Long, dry, cold > Coniferous trees
coniferous forests) conifers winters >Squirrels
> Short, wet, > Foxes
warmer summer
Tundra Arctic Permafrost (layer > Long, cold > Low-growing
of permanently winters plants with
frozen ground) > Short, cool shallow root
summers systems (mosses,
small shrubs, and
grasses)
> Lemming
> Arctic foxes

Tundra Alpine Located at very > Highland climate > Himalayan tahr
(mountains) high altitudes > One of the > Snow leapord
where trees coldest biomes
cannot grow

Aquatic biomes

a) Freshwater (salt-free water)

 Rivers (wide bodies of water that flow in one direction)
 Streams (narrow bodies of water that fow in onde direction)
 Ponds (small standing bodies of water)
 Lakes (lakes are large standing bodies of water)
 Wetlands (marshes, swamps)

b) Marine (saltwater)
 Coral reefs (living communities within tropical oceans)
 Estuaries (regions where freshwater streams or rivers merge with the ocean
 Oceans
Relationships Between Organisms

5 types of interactions:

1. Predation—occurs when one animal kills and eats another animal

2. Competition- occurs between organisms that both need the same resource

- Symbiosis -

3. Mutualism- relationship when two organisms both benefit from interacting

4. Parasitism- relationship when one organism harms another organism
5. Commensalism- relationship when one organism is helped and one organism is not harmed

Matter in Ecosystems

Carbon cycle:

 Decomposers recycle some carbon into the soil and release carbon dioxide into the atmosphere
 Plants absorb carbon dioxide to make food through photosynthesis
 Carbon dioxide is also returned to the atmosphere through cellular respiration

Nitrogen Cycle:

 Converts unusable nitrogen into usable form

 Humans speed up the nitrogen cycle by adding nitrogen-containing fertilizer added to cropland

Nitrogen fixation—nitrogen in the air combines with other elements to form compounds that are
deposited in the soil

These compounds are converted into organic compounds by certain bacterias

Nitrification—these organic compounds are converted by bacteria into nutrients that can be absorbed
by plants

After going through the food cycle, nitrogen is then decomposed back into the soil along with the
remains of dead plants and animals who all of which, contain nitrogen

A bacteria convert s the nutrients in the soil back to atmospheric nitrogen in the air
Sexual and Sexual Reproduction

 Sexual reproduction—the reproduction of living things combining male and female reproductive
cells

 Genes from both parents, half from each, are passed through meiosis, a type of cell
division.
 Advantage: because genes are passed through from two parents, the offsprings from
sexual reproduction are diverse
 Disadvantage: because two opposite sexes are needed for sexual reproduction, an
organism needs to find an opposite sex to be able to reproduce

 Asexual reproduction—the reproduction of living things in which offspring are made by just one
parent

 Asexual reproduction is done by binary fission, budding, or fragmentation.

 All the genes from one parent are passed through mitosis, a type of cell divisiom.
 Advantage: because only one organism is needed for sexual reproduction, an organism
does not need to find another organism to reproduce
 Disadvantage: because only the genes from one organism is passed to the offspring,
there is not much diversity passed through
Mitosis

 A form of asexual reproduction that produces two identical daughter cells

 Occurs so a multicellular organism can grow and develop
 Occurs to replace damaged or dead cells, except cells in kidneys and lungs.

Steps:

Interphase—cells grow in size. Inside the nucleus, the chromosomes are duplicated, but are still in the
form of loosely packed chromatin fibers.

1. Prophase

Early Prophase—each chromosome appears as two identical strands called chromatids, which is either
of the two strands that form when a chromosome copies itself. The chromatids are then joined by a
single centromere, which is a part of the chromosome to which the spindle fiber attaches to to divide
them.

Late Prophase—the chromosomes get thicker, the centrioles move to opposite ends of the cell, and
themembrane around the nucleus goes away.

2. Metaphase—the chromatids line up in the middle of the cell by attaching themselves to the fibers of
the spell spindle

3. Anaphase—the pairs of chromatids then seperate from each other and move toward opposite ends of
the cell

4. Telophase—a new membrane forms around each of the two groups of chromosomes

Cytokinesis—the cytoplasm the divides to form two separate daughter cells.

Meiosis

 A type of cell division that goes through two rounds of the 4 mitotic step, resulting in
reproductive cells with half the original number of chromosomes
 An egg cell and a sperm cell combine to begin development of a new individual
 Sexually produced offspring are never identical to either of their parents

Meiosis I-> Phases of Mitosis

Meiosis II -> Phases of Mitosis, but the number of chromosomes is reduced to half the original number
in each sperm and egg cell, telophase and cytokinesis happens at the same time