6: Perpetuation of Life Flashcards
Plants reproduce through three types
asexual, sexual, and vegetative
Offsprings are produced from the vegetative unit produced by a parent without any fusion of sex cells or gametes.
Asexual Reproduction
can be seen in unicellular organisms such as yeast or bacteria. The content of the parent cell divides into 2, 4, or 8 daughter cells.
Fission
bud-like growth formed on one side of the parent cell. As soon as the bud separates from the parent cell, it becomes a whole new organism
Budding
occurs in filamentous algae. It occurs as a result of accidentally breaking off a filament into many fragments. Each new fragment may give rise to a new organism through cell division
Fragmentation
occurs in lower plants, such as pteridophytes and byrophytes. During this type of asexual reproduction, special reproductive units develop asexually on the body of the parent.
Spore formation
These special reproductive units are called
spores
Here, a vegetative part of the plant, such as the root, stem, leaf, or bud, is detached from the body of the parent and grows into a daughter plant that is independent.
Vegetative Reproduction
involves the fusion of female and male reproductive cells (gametes).
Sexual reproduction
gametes contain only half the genetic material (chromosomes) for a new organism to exist.
haploid
The fusion of gametes
fertilization
When the zygote undergoes further development, it gives rise to a new individual that is ______.
diploid
At the beginning stages of sexual reproduction, ______ occurs.
meiosis
multicellular
Spirogyra
unicellular
Chlamydomonas
unicellular algae that is found in freshwater ponds.
Chlamydomonas
are filaments found in flagellates
Flagella
When Chlamydomonas undergoes asexual reproduction, it is through
zoospores
The zygotes then develop a thick wall around itself
zygospores
A free-floating algae found in freshwater ponds.
SpirogyraSpirogyra
occurs first when filaments break into smaller fragments. Then, each fragment grows into a new organism by cell division.occurs first when filaments break into smaller fragments. Then, each fragment grows into a new organism by cell division.
Vegetative reproduction by fragmentationVegetative reproduction by fragmentation
when filaments conjugate to form a ladder-like appearance, starts when two filaments lie very close to each other.
Scalariform conjugation
The cells of the two filaments connect with each other through a __________
conjugation tube
these plants live for only one year. The plants that produce seeds and flowers within just one season are termed as annuals
Annuals
plants that live for two seasons, and complete their life cycles within these two seasons. During the first year, the plant is in a vegetative state. In the second year, the plants produce flowers, fruits, or seeds and then they perish
Biennials
plants that live for several years. The vegetative state of these plants may last from one year to several years. In the year following their vegetative state, they produce flowers, seeds, or fruits
Perennials
perennial plants that reproduce only once during
their lifetime and then die
Monocarpic
has a soft stem, and only bears a few leaves. The size and shape of the leaves remain the same. It does not respond to stimuli nor does it produce flowers.
juvenile shoot
has well-developed stems and leaves. The size and shape of the leaves change. It also responds to stimuli and can produce flowers.
adult shoot
The plant’s flowering is affected by light
photoperiodism
The plant’s flowering is affected by temperature
vernalisation
is when low temperatures occur, and this stimulates the early formation of flowers.
Vernalisation
is the response of the plant to the duration of dark and light per day. This determines its growth and flowering.
Photoperiodism
means a flower has both carpels and stamens
bisexual
means a flower has only a staminate or pistillate
unisexual
a plant hormone that assists in growth and reproduction.
Gibberellin
comprise the calyx.
Sepals
comprise the corolla.
Petals
male reproductive organ of a flower
androecium
female reproductive organ of a flower
gynoecium
Each __________ is made up of distinct layers of cells when mature.
microsporangium
The outermost layer is the ________. It has a middle layer of cells with thin walls.
epidermis
The innermost layer is the _______, which consists of large cells. It nourishes the developing grains of pollen.
tapetum
Microspore mother cells undergo _______.
meiosis
exine is made up of a durable substance called
sporopollenin
The outer layer is the
exine and thin spaces (germ pores)
grows out of the pollen grain through the germ pores.
pollen tube
The inner layer is the
cellulosic wall (the intine)
moves towards the periphery.
microspore
The main part of the ovule is bounded by two coverings
integuments
The ovule is attached to the ovary via a stalk
funiculus
The basal part of the female gametophyte structure
chalaza
contains one or more ovules (megasporangia), which act as future seeds
ovary
develops as a type of projection from the placenta in the ovary.
ovule
Within the nucleus, a single ________ cell becomes larger and it becomes the megaspore mother cell.
hypodermal
This cell undergoes ___________, and then gives rise to four haploid megaspore cells.
meiotic division
The enlarged structure, shaped like an oval and with 8 nuclei, is known as the _______
embryo sac
Cell membranes and nuclei develop around the nuclei, except the two at the center of the sac, which is now termed as the _______
central cell
These are provided with buds which develop into a new plant and are therefore used to carry out vegetative propagation of the plant in the field.
Vegetative Reproduction in Angiosperms
The process by which animals propagate on earth and it is also the process through which genetic materials are transferred to offspring.
Animal Reproduction
The formation of identical twins by the separation of two identical cells in the early embryo is a form of
asexual reproduction
occurs when a new individual is formed from the union of two sex cells, or gametes.
Sexual reproduction
the zygote develops into a new organism.
mitotic division
The _________ are formed in the sex organs, or gonads (the testes and the ovaries), and are haploid.
gametes
The process of sperm formation
spermatogenesis
The process of egg formation
oogenesis
Virgin birth is common in many species of arthropods.
parthenogenesis
Some species are exclusively all female
parthenogenetic
Another variation in the reproductive strategies used by animals is
hermaphroditism
The change from female to male is
protogyny
the change from male to female is
protandry
Recent evidence suggests that the __________ appears to have been highly conserved during the evolution of vertebrate groups.
sex-determining gene (SRY)
commonly occurs among organisms in the ocean, where water allows for the rapid dispersion of sperm or ova towards others of the same species.
External fertilization
is the introduction of the male gamete into the female’s reproductive tract.
Internal fertilization
is when the eggs are deposited outside the mother’s body after fertilization.
Oviparity
The fertilized eggs are retained within the mother in order to complete their development. The embryos still take all of their nourishment from the egg yolk. The young are thus fully developed when they hatch.
Ovoviviparity
is found in almost all mammals. The young develop within the mother and takes its nourishment directly from their mother’s blood, as opposed to egg yolks.
Viviparity
In most cartilaginous fish most fertilization is _____.
internal
In internal fertilization, the male introduces sperm into the female by means of a modified _______.
pelvic fin
In Amphibians, gametes from the males and females are released through the __________.
cloaca
The shells of reptile eggs are _____, and this allows for better withstanding of environmental conditions.
leathery
As the eggs pass through the ________, the glands secrete the egg whites and the hard shells that distinguish bird eggs from reptilian eggs.
oviduct
Most birds are also _______, meaning that they keep a stable body temperature.
homeotherms
the embryo that develops within the cavity filled with fluid is surrounded by a membrane called an amnion.
amniotic eggs
is an extra-embryonic membrane and develops outside of the body of the embryo.
amnion
_______ in females is the cyclic release of an egg from the ovary.
Ovulation
The period of sexual receptivity
estrus
the reproductive cycle is therefore called
estrous cycle
The most primitive mammals, the monotremes, are __________
oviparous
derives its nutrients from the mother’s blood, since fetal and maternal blood vessels are in close proximity.
fetus
deduced the classical principles of genetics in 1865. He based his deductions on the results of breeding experiments with peas.
Gregor Mendel
genetic composition
genotype
their physical appearance
phenotype
is the term for the deductions of Mendel.
Mendelian genetics
in the form of meiosis involves the daughter cell inheriting only one member of each chromosome pair.
Cell division
Chromosomes exchange materials during ________, leading to the linked genes’ recombination.
meiosis
The first evidence for the existence of enzymes came in 1909, through the study of the disease called ________ The disease results from a genetic defect that results in problems with the metabolism of phenylalanine, an amino acid.
phenylketonuria
who formed the basis for present-day molecular biology.
James Watson and Francis Crick
purines
adenine (A), guanine (G)
pyrimidines
cytosine (C), and thymine (T)
Two strands of DNA can separate to serve as templates for a new strand. This would be specified by base pairing.
semiconservative replication
This process is called semiconservative replication, because one strand is conserved in the
progeny DNA molecule
The enzyme that catalyzes DNA replication
DNA polymerase
going both forwards and backwards
bidirectional
going only one direction
unidirectional
directed by genes.
Protein synthesis
the sequence of nucleotides in a gene in the DNA is copied to the corresponding sequence of nucleotides in mRNA.
transcription
the sequence of nucleotides in the mRNA determines the sequence of amino acids in the proteins.
translation
mediated by RNA polymerase It separates the two strands of the double helix and constructs an mRNA molecule by adding nucleotides one at a time.
transcription
determines the sequence of amino acids in the protein.
translation
Each tRNA has three nucleotides that form an
anti-codon
building blocks of proteins
Amino acids
mRNA
messenger RNA
tRNA
transfer RNA
