Evolution and Reproduction Flashcards
Ovaries function
to produce eggs for fertilisation + produce hormones
epididymis function
coiled tube in which sperm mature
fallopian tubes function
to transport sperm toward the egg
seminiferous tubules function
produces, maintains and stores sperm
uterus function
Accepts a fertilised egg till the baby is mature enough for birth, it is where the foetus develops during pregnancy.
Male reproductive system
Male sperm are produced in the testes which are found in the scrotum. When the male is about to ejaculate sperm the penis becomes erect and the sperm is forced to travel to the uretha through the ejaculatory duct. It is mixed with fluid from the seminal vesicles and the prostate gland this mixture is called semen.
Where are male sperm produced
in the testes which are found in the scrotum
what happens when the male is about to ejaculate sperm
the penis becomes erect and the sperm is forced to travel to the uretha through the ejaculator duct
what is semen
the sperm is mixed with fluid from the seminal vesicles and the prostate gland to form the mixture of sperm
Female reproductive system
The female reproductive organs are called the ovaries. AT birth these contain round 1-2 million ova. After puberty, one egg ripens each month and is released- this process is called ovulation. About 500 eggs are released during a woman’s lifetime before menopause is reached, usually around the age of 50.
When an egg is released from the ovary, it travels down the fallopian tube to the uterus, the walls of which thicken after ovulation. These walls are richly supplied with blood to provide nutrients for the off if it fertilised. If no pregnancy results the uterus lining breaks down and passes out of the body as menstrual flow. The 28 day cycle of ovulation and menstruation is controlled by chemicals int he bloodstream called hormones.
The cervix is a ring of muscle at one end of the uterus where it joins with the vagina. It is here that male sperm are deposited and it is down this tube that a baby travels at birth.
what are the female reproductive organs called
the ovaries
at birth how many eggs does the ovary contain
1-2 million
explain ovulation
After puberty, one egg ripens each month and is released
how many eggs are released during a woman lifetime
around 500 eggs
menopause occurs..
around the age of 50
what happens when an egg is released from the ovary
When an egg is released from the ovary, it travels down the fallopian tube to the uterus, the walls of which thicken after ovulation. These walls are richly supplied with blood to provide nutrients for the off if it fertilised.
what happens if no pregnancy occurs
If no pregnancy results the uterus lining breaks down and passes out of the body as menstrual flow. The 28 day cycle of ovulation and menstruation is controlled by chemicals int he bloodstream called hormones.
what controls the 28 day cycle of ovulation and menstruation
chemicals in the bloodstream called hormones.
what is the cervix
The cervix is a ring of muscle at one end of the uterus where it joins with the vagina
where is male sperm deposited
at the vagina and it travels down the fallopian tubes to the cervix
Fertilisation
in sexual intercourse the erect penis is inserted in the females vagina and semen is ejaculated. This contains around several hundred million sperm. The sperm swim up through the cervix and uterus to the oviducts. If a sperm and egg meet here, fertilisation occurs- the fertilised egg is called a zygote. This starts producing new cells by dividing as it travels down and embeds itself in the uterus. At this stage it is known as an embryo: after around 8 weeks when the organs have formed it is called a foetus. It gets its food and oxygen, and gets rid of waste products through an organ called the placenta: the placenta brings the blood of the foetus and the mother into close contact although they never mix.
placenta function
Provided the foetus with its food and oxygen, and gets rid of waste products. The placenta brings the blood of the foetus and the mother into close contact although they never mix.
Sexual intercourse occurs when
the erect penis is inserted in the females vagina and semen is ejaculated
how much sperm is ejaculated
several hundred million sperm
Where do the sperm swim
through the the cervix and uterus to the oviducts
where does fertilisation occur
if a sperm and egg meet at the oviducts
what is a fertilised egg called
a zygote
at what stage is an egg considered an embryo
This starts producing new cells by dividing as it travels down and embeds itself in the uterus.
when is the embryo considered a foetus
after around 8 weeks when the organs have formed
Birth
The time from conception to birth is approximately 40 weeks- this is called the gestational period. babies born before 37 weeks are said to be premature.
First the cervix widens. Then hormones cause the uterus to contract and push the baby out, normal head first. The umbilical cord connecting the baby to the placenta is cut, and the placenta is there expelled as afterbirth.
what is the gestational period and how long does it last
The time from conception to birth and is approximately 40 weeks
when is a baby considered premature
when a baby is born before 37 weeks
what connects the placenta to the baby
umbilical cord
what is afterbirth
when the placenta is expelled
IVF stands for
in- vitro fertilisation
what is ivf
the process of fertilising an egg with sperm outside the human body
how does ivf work
1) an egg is isolated from the mother
2) sperm are analysed to determine the most likely to be successful
3) optional- gender is chosen
4) The eggs + sperm meet and the developing eggs are grown; more then one egg is often required
5) The embryo is implanted back into the mother or a surrogate (rented womb)
how developments in technology have advanced biological understanding,
Ivf is a major treatment of infertility and highly utilised treatment option of assisted reproductive technology. The advances in technology over the past decade for ivf have made this route of achieving pregnancy very popular amongst patients. The development of ivf allows women to be provided with the possibility of a pregnancy when they previously might have faced difficulties.
advantages of ivf
Ivf provides people who previously may have had difficulty falling pregnant to try pregnancy in a new way.
For single people and for gay people it also is a way to allow them to fall pregnant
disadvantages of ivf
not morally right in some cultures
some do not have access to the technology
expenses
is not always successful
Scientific evidence that present day organisms have evolved from organisms in the past
anatomy
embryology
molecular biology
fossil record
anatomy
species may share similar physical features because the feature was pressed in a common ancestor (homologous structures)
Homologous
homologous structures show individual variation on a common anatomical theme. These are seen in organisms that are closely related
analogous
analogous structures have very different anatomies but similar functions. These are seen in organisms that are not closely related, but live in similar environments and have similar adaptions
vestigial structures
vestigial structures are anatomical remnants that were very important in the organisms ancestors but are no longer use din the same way
embryology
organisms that are closely related may also have physical similarities before they are even born, we can see this through embryos
homologous embryonic structures
reflect that the development programs of vertebrates are variations on a similar plan that existed in their last common ancestors
molecular biology
at the most basic level all living organisms share:
DNA
genetic codes- the same or highly similar
the same basic process of gene expression
the same molecular building blocks, such as amino acids
molecular biology features suggest…
that all living things are descended from a common ancestor, and that this ancestor had DNA as its genetic material, used the genetic code, and expressed its genes by transcription and translation
what is natural selection
the process whereby organisms better adapted to their environment tend to survive and produce more offspring
how do we determine the age of fossils
through its position and placement in the rock,
a fossil found deeper/further down in the rock will be older than one found close to the surface
this is called stratigraphy
why are pesticides becoming more popular
because plants and insects are becoming resistant to the pesticides, this causes it to spread and will become a huge problem in the future, as we will no longer be able to use certain plants as they will become harmful and dangerous
how can scientists date fossils
due to their positioning in the rock layers
fossils document…
the existence of previous species showing that different organisms have lived on earth during different periods of the planets history
features of natural selection
- organisms with heritable features that help them survive and reproduce in a particular environment tend to leave more offspring than their peers
- if this continues over generations the heritable features will become more common in the population
- the population will not only evolve, but will become adapted and better suited to its environment
environmental facors role in the survival or organisms in a population
environmental factors effecting population growth include nutrient, water and space availability as well as predation and disease
variations within populations mean…
some members are equipped with features that allow them to be better adapted which therefore increase their survival rates and through reproduction pass these advantages through genes
What can gene mutations do
they can cause gene variation, the variations often alter gene activity or protein function which can introduce different traits in an organism. If this trait is advantageous and helps the individual survive and reproduce, the genetic variation is more likely to be passed to the next generation. THIS is natural selection.
