BIOENERGETICS AND
PERPETUATION OF LIFE
LIFE SCIENCE
Lesson Objectives
At the end of the lesson, learners should be able to:
1. describe how unifying themes (e.g., structure and
function, evolution, and ecosystems) in the study of
life show the connections among living things and
how they interact with each other and with their
environment
2. describe the different ways of how plants and
animals reproduce
LIFE SCIENCE
Energy for Life
• Energy is the ability to do
work. You often see
energy at work in living
things, such as in a boy
running, a bird flying, or a
cat eating. There are
obvious ways that living
things use energy, but
living things also use it
inside the body.
LIFE SCIENCE
How Do Organisms Get
Energy?
Autotrophs are organisms that make their
own food. Most autotrophs use energy
from sunlight to make their food. They are
also called producers.
Producers make food not only for
themselves but for other living organisms as
well.
LIFE SCIENCE
How Do Organisms Get
Energy?
Organisms that cannot make their own
food obtain food by consuming other
organisms. These organisms are referred to
as heterotrophs.
LIFE SCIENCE
Energy-Giving Molecules:
The Glucose and ATP
Glucose is made during the process of
photosynthesis. With the help of light energy from
the sun, water, and carbon dioxide, plants
create glucose, where chemical energy is stored
in a concentrated and stable form.
The stored energy in glucose is released
in a reverse reaction of photosynthesis
called cellular respiration.
Adenosine triphosphate (ATP) molecules store
smaller amount of energy, but each molecule
releases enough energy to do the work within
the cell. It is the energy-carrying molecule used
by the cell,
LIFE SCIENCE
Photosynthetic Organelles
Photosynthetic pigments are unique pigments found in all
photosynthetic organisms such as plants and some bacteria.
These pigments capture light energy necessary for
photosynthesis.
• Chlorophyll a and chlorophyll b are
green pigments that absorb all
wavelengths of light in the red, blue,
and violet ranges.
• Carotenoids are yellow, orange,
and red pigments. They absorb light
in blue, green, and violet ranges.
• The Pigment found in red algae,
called the phycobilins, which give
them their reddish color, absorb light
in blue and green ranges.
PERPETUATION OF LIFE
LIFE SCIENCE
Reproduction in
Plants
Sexual Reproduction
Sexual reproduction in plants involves
the fusion of the parent’s gametes,
which gives rise to an individual that
has the genes of both parents.
LIFE SCIENCE
Flower
Sexual
1
Reproduction
• The female reproductive part of the flower
or pistil has stigma, style and ovary.
• The ovary contains the ovule that has the
egg nuclei.
• The stamen on the other hand, is the male
part of the flower. It has the anther that
produces pollen grains, which contain the
sperms.
LIFE SCIENCE
Flower
Sexual
1
Reproduction
• Pollination is the transfer of pollen
from the anther to the stigma of the
flower.
• One sperm fertilizes the egg and
becomes the embryo, a diploid (2n).
The other sperm fertilizes the two
polar bodies and becomes the
endosperm, a triploid (3n). The
endosperm is a nutrient-rich tissue
which serves as nourishment for the
growing embryo. This process is called
double fertilization.
LIFE SCIENCE
Seed
Sexual
2
Reproduction
• The seed usually consists of a
seed coat, embryo, and
endosperm.
• The seed coat protects the
internal parts of the seed
against external factors. It also
helps in the dormancy of the
seed. The endosperm serves as
the food for the growing
embryo.
LIFE SCIENCE
Reproduction in
Plants
Asexual Reproduction
Asexual reproduction is a type of
reproduction that creates genetically
identical offspring. The offsprings that
arise from asexual reproduction can
be considered clones.
LIFE SCIENCE
Asexual
Reproduction
1
Vegetative Reproduction
In plants, asexual reproduction
usually arises from the
vegetative parts (stem, roots,
and leaves) of the plant. This is
also called vegetative
reproduction.
LIFE SCIENCE
Asexual
Reproduction
2
Stolon or Runners
Stolons or runners are specialized
stems of some plants such as the
strawberry.
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Asexual
3
Reproduction
Rhizomes
Rhizomes are stems which grow
horizontally under the ground.
LIFE SCIENCE
Tubers
Asexual
4
Reproduction
Tubers are used both for starch
storage and give rise to new
plants. An example is potato
plants
LIFE SCIENCE
Bulbs
Asexual
5
Reproduction
Bulbs are underground stems
that give rise to a new plant,
such as in the case of onions
and lilies.
LIFE SCIENCE
Corm
Asexual
Reproduction
6
Corm differs from the bulb
since it is also used for
storage of food of the plant,
sometimes referred to as the
bulbotuber. Corms give rise
to new small corms in their
nodes called cormels.
LIFE SCIENCE
Reproduction in Animals
The process wherein a sperm and egg
unite is called fertilization. The zygote
divides and differentiates into an embryo.
The embryo then grows and develops until
the time of birth or hatching.
Even earthworms which has two sexes
(hermaphrodite), do cross-fertilization.
Some species of animals undergo selffertilization like that of the tapeworms
in the intestine.
LIFE SCIENCE
Reproduction in Animals
Frogs, crabs, corals and most fishes undergo
external fertilization. That is, meeting of
gametes does not happen inside the body
of the female animal, but in the open
environment or outside the body.
Human Reproduction
Most fertilization happens inside the
body of the female species, wherein
the male deposits the sperm in the
female’s reproductive organ during
mating. This is called internal
fertilization.
LIFE SCIENCE
4
Reproduction in
Animals
Asexual Reproduction
Some animals are also capable of
asexual reproduction, which
usually occur when sexual
reproduction is not possible.
LIFE SCIENCE
Budding
Asexual
1
Reproduction
Budding involves the splitting of new
individuals from an existing organism
by forming small projections, called
buds, from the parent’s body. Animals
such as hydra undergo this type of
asexual reproduction.
LIFE SCIENCE
Asexual
2
Reproduction
Fragmentation
Fragmentation and regeneration are
type of asexual reproduction wherein
a single parent breaks into parts that
give rise to new individuals. Sponges,
planaria, and starfish are examples of
animals that exhibit this type of
asexual reproduction.
LIFE SCIENCE
Asexual
3
Reproduction
Parthenogenesis
Parthenogenesis is a form of asexual
reproduction in some animals that
give rise to growth and development
of an embryo without fertilization in
animals.
LIFE SCIENCE
Transfer of Genes from Parent to Offspring
Asexually reproduced offspring tend to
have very similar characteristics from its
parents. One parent alone passes on a
duplicate of all its genes to the newlyproduced individual.
Sexual reproduction yields fewer
offspring but it results in a greater
gene variation. Both the mother and
the father contribute to the
offspring’s genes.
LIFE SCIENCE
The Use of Technology in
Reproduction
• Selective breeding or artificial
selection is the process by
which humans breed animals
and plants that contain
particular desired traits.
• Biotechnology is defined as
the use of living systems or
organisms to create or
develop new products.
The Use of Technology in
Reproduction
1
Genetic Engineering
Genetic engineering is the process by
which genes from one organism is
transferred into another organism of an
entirely different species. In one method
of genetic engineering, part of an
organism’s DNA is joined with the DNA of
another organism. The combined DNA is
called recombinant DNA
LIFE SCIENCE
The Use of Technology in
Reproduction
2
In Vitro Fertilization
In vitro fertilization is a process by which a
sperm fertilizes an egg outside the body.
This is usually done in the laboratory,
hence the name, “in vitro” (Latin: in
glass). This technique involves the
removal of matured ovum (egg) from the
woman’s ovary.
LIFE SCIENCE
The Use of Technology in
Reproduction
3
Plant Tissue Culture
This technique is used to grow, maintain,
and reproduce plant cells and tissues in a
nutrient media under controlled sterile
conditions. Plant tissue culture is a
technique widely used to produce plant
clones, and is often called
micropropagation.
LIFE SCIENCE