Science Unit 8 SEXUAL REPRODUCTION Flashcards
Definition of Reproduction?
- It is the production of new organisms.
- It is to ensure the continuation of life of a living organism
- Two types: Sexual and Asexual
Characteristics of Sexual Reproduction?
- It involves the fusion of the nuclei of two sex cells to form a fertilised egg (also known as zygote)
- It typically involves two parents
- The two sex cells are: Sperm and Egg (Both are gametes)
EXAMPLE: Fertilisation in Humans.
Characteristics of Asexual Reproduction?
- It does not involve the fusion of the nuclei of sex cells.
- It typically involves only one parent.
EXAMPLE: A bacterial cell divides into two identical “daughter cells”.
Definition of Heredity?
- It is the passing down of genetic material from one generation to the next during Sexual Reproduction.
What happens during Fertilisation?
A sperm and Ovum unite to form a new diploid organism
- Gamete are Haploid (Sex cells)
- Zygote is Diploid (Fertilised Egg)
Sex cells ->
Gamete (Haploid)
Fertilized egg ->
Zygote (Diploid)
Definition of Heredity?
It is the passing down of genetic material from one generation to the next during reproduction.
What is genetic material?
- It is found in the nucleus of the sex cell
- It contains a set of instructions that guide the development and treaits of the offspring
What are traits?
They are determined by genes.
Exaplain how Genetic material is passed down during reproduction:
When the nuclei of the sex cells fuse together, they form a zygote which contains the genetic material of both parents, though it is not entirely the same as the parents.
Definition of Variation?
- It refers to the differences in the combination of genetic material among individuals within a population.
Explain the process of inhereting traits:
- Inheriting traits is a random process. This means that offspring can inherit any possible combination of traits from its parents.
Reasons of inheriting traits:
- These sex cells combine randomly to restore the full set of genetic material in the off spring.
- They contain both the parents’ genetic material, but not completely the same comnbination as the parents. (Each parent carries two genetic material [Diploid])
(Their sex cells contain only one set of genetic material [Haploid])
Examples of inheritable diseases:
Sickle Cell Anaemia, Albinism, Cystic Fibrosis
Definition of Puberty?
It is the period of human growth and physical developments in which a girl or boy matures sexually.
Definition of Hormones:
A hormone is a chemical messenger in the body that regulates various functions like growth, metabolism, and mood.
Theory of “Which sperm won, Which egg present”
As the sex cells fuse together randomly, the traits inherited by the off spring are determined by chance.
Definition of Puberty?
It is the period of growth and physical development in which a girl or boy matures sexually.
Traits of PUBERTY in a GIRL:
- When: Typically 10-12 years old
- Sex Hormones: Oestrogen and Progesterone
- Common Changes:
1. Breats enlarge
2. Hips become rounder and broader
3. Growth of pubic hair and armpit hair
4. Increased height and weight
5. Ovulation begins
6. Menstruation begins
What happens during puberty? (2 things, Hormone + Maturation of sex organs)
- The production of sex hormones (Testostrone {MALE}, Oestrogen and Progesterone {FEMALE}
- Sex organs become fully functional and begin to produce mature sex cells.
Why is it important for the Hips to become rounder and broader? (sexual maturation of females)
- A broader pelvis provides a more accommodating birth canal, which is essential for childbirth.
- Increased fat deposition in the hips and thighs helps support future reproductive functions, including pregnancy and breastfeeding.
Traits of PUBERTY in a BOY:
- When: Typically between 12-14 years old
- Sex hormones: Testostrone
- Common changes:
1. Production of sperm
2. Enlarged penis and testes
3. Voice Deepens
4. Growth of facial hair, pubic hair and armpit hair
5. Increased height and weight
6. Increased muscle strength
Why do Males have muscle strengthening during puberty but not Females?
Estrogen: In females, while estrogen also contributes to muscle development, its effects are less pronounced compared to testosterone. Estrogen influences muscle growth but does not stimulate the same level of muscle hypertrophy as testosterone.
Whats the function of the Male reproductive system? (P.S.T)
- To Produce, Store and Transport sperm
- To produce and secrete male sex hormone (Testostrone)
- Penis: To discharge sperm into the female reproductive system
What is the function of the Female Reproductive system?
- It produces mature eggs for reproduction (during ovulation)
- To produce female sex hormones (Oestrogen and Progesterone)
Parts of the male reproductive system:
- Sex Glands (Produces nutrient fluid to nourish the sperm)
- Sperm duct (Carries sperm from Testes to Urethra
- Urethra (Allows sperm to pass through during ejaculation, Allows urine to be removed from the body)
- Penis (Organ outside of the body that deposits semen containing sperm in a woman’s vagina)
- Testis (Produces makle sex hormones and Sperm {Plural of sperm cell})
- Scrotum (Holds Testes outside of body)
The 4 stages of Fertilisation:
- During ovulation, an ovary releases a mature egg cell into the oviduct. Meanwhile, the semen contain millions of sperm is discharged into the vagina during sexual intercourse.
- The sperm swim toward the oviduct from the vagina to meet the egg cell. While the egg is surrounded by millions of sperm cell, only one sperm cell can penetrate the egg and fertilise it.
- The fertilised egg begins to travel down to the uterus, dividing into a ball of cells called an embryo
- When the embryo reaches the uterus, it implants itself into the uterine wall before gradually developing into a foetus, leading to a baby after about nine months.
What is Menstruation?
Definition: It is the discharge of the uterine lining, blood and unfertilised egg through the vagina toIt is a cycle of events that repeats itself every month.
- After puberty, a woman will experience the mestrual cycle when she is not pregnant.
It lasts typically about 28 days but can vary from person to person.
Definition of Implantation?
- It refers to the process by which a ferilised egg attaches itself to the uterine lining and becomes embedded in it.
Key days of the menstrual cycle.
1-5 (Mensturation)
6-9 (Uterine repair and thicken)
10-15 (Ovulation)
16-28 (Maintained uterine lining)
Definition of Substance Abuse?
Repeated and excessive use of certain substances that give rise to negative consequences for an individual (Drug abuse, Alcoholic, Smoking)
Effects of substance Abuse on Foetus during pregnancy:
- Babies born prematurely
- Babies born with low birth weight
- Smoking of mother can affect foetus’ heart, lungs and brain.
- Drinking and Drug abuse can affect the development physically, intellectually and behaviourly in a child.
Negative impacts of premarital sex:
- Increased chance of unwanted pregnancy
- Increase the risk of sexual transmitted infections (STIs)
Explain the Rhythm Method of Temporary birth control:
Act: A woman uses a calander to check her menstrual cycle or relies on her body temperature to determine the day of ovulation.
How it prevents: Withdrawal of sexual activity during ovulation though not reliable as pregnancy can still occur
Explain the use of Condom of Temporary birth control
- Condom (Male), Diaphragm (Female)
- Prevents fertilisation by blocking the sperm from entering the Uterus.
Explain Intra-Uterine Device (IUD) of Temporary birth control:
- Inserted into the uterus by a medical specialist.
- Prevents the fertilisation or implantation of an embryo.
Explain Birth Control Pills of Temporary birth control:
- Pills contain female sex hormones to prevent ovulation
- Prevents the ovaries from releasing eggs
Explain Spermicide of Temporary birth control:
- Typically placed in the vagina before sexual intercourse
- Contains chemicals that kill sperm in the vagina, preventing fertilisation.
Reversible methods of Birth control management:
- Rhythm method
- Male and Female condom types
- Intra-Uterine Device (IUD)
- Birth Control Pills
- Spermicide
Irreversible methods of Birth control management:
- Tubal Ligation (Female) {Oviducts are surgically cut and tied so sperm cannot meet the egg anymore for fertilisation}
- Vasectomy (Male) {Sperm ducts are surgically cut and tied to block passage of sperm from Testes to Urethra
Definition of Abortion:
A deliberate termination of a pregnancy (NOT a form of birth control)
Negative impacts of an Abortion:
- Woman can lose excessive amounts of blood which can be fatal.
- Risk of Infection post-procedure.
- Woman may be infertile due to permenant damages to the Uterus.
Ways of transmitting STIs:
- Through sexual intercourse
- Through blood transfusion
- Through the sharing of contaminated needles used by an infected person.
- From a mother to an infant during childbirth or Breast-feeding
- Syphilis symptoms and long-term effect:
Symptoms: Fever, Fatigue, Sores on the mouth, throat and genitals, Headache, Weigh loss, Patchy hair loss,
Long-term: Blindness, Infertility, Major brain and heart damage, Paralysis
Types of STIs (Bacteria or Virus):
- Syphilis (Bacteria)
- Gonorrhoea (Bacteria)
- HIV (Virus)
Definition of STIs?
Sexually Transmitted Infections are infectious diseases that are passed from one person to another through sexual contact.
- Gonorrhoea symptoms and long-term effect:
Symptoms: Burning Sensation when urinating, Discharge of pus from genitals, Pain in the lower abdomen.
Long-term effects: Infertility, Long-term abdominal or pelvic pain
- Human Immunodeficiency Virus symptoms and long-term effects:
Symptoms: Flu-likesymptoms, Extreme exhaustion, Chronic fever, Chills, Night sweats, Rapid weight loss, Severe diarrhoea, decrease appetite
Long-term effect: Weakened immune system (When HIV progresses to AIDS from 8-10 years time), Death
How do Anti-biotics work:
They are substances designed to kill or stop the growth of harmful bacteria. They target specific structures and processes unique to bacterial cells, such as their cell walls.
Factors contributing to the growth of the world population:
- Medical advancements
- Increased efficient food production
- Improved transportation
- Improved sanitation
How does medical advancement contribute to the growth of the world population?
- New drugs and vaccines protect people against diseases.
- New diagnostic technologies provide fast and accurate diagnoses to stop the problem from further spreading at an earlier time.
- Inventions such as pacemakers and lung machines.
(All these factors help prolong the life of people)
How does Improved transportation contribute to the growth of the world population?
- Advancements in air, land and sea transportation allows for faster distribution of food and medicinal sources to regions across the world for people to access for survival.
How does Increased food production contribute to the growth of the world population?
- Advanced technology allows for cultivation of crops despite soil conditions AND the development of pest-resistant crop varieties.
- New drugs introduced to farmed animals to produce more abundant and affordable food (Improve access)
How does Improved sanitation contribute to the growth of the world population?
- Improvements in sanitation and waste management help prevent the contamination of food and water. (Filtration systems etc.)
- Prevents onset of deadly diseases such as Typhoid and Cholera.
