• Reproduction is the process that makes more of the same kind of an organism
• There are two types of reproduction, asexual and sexual reproduction

Asexual Reproduction

• The process resulting in the production of genetically identical offspring from one parent
• It is the formation of a new organism, without the involvement of gametes or fertilization

Bacteria

• Bacteria reproduce asexually by binary fusion
• Inside an individual bacterium, the DNA replicates
• Then the cell divides into two, with each daughter cell containing a copy of the parental DNA
• Once the daughter cells have grown, they can also reproduce

Fungi

• Fungi can reproduce asexually by producing spores, which may be formed inside a structure called a sporangium
• When ripe, the sporangium bursts open allowing the spores to be dispersed
• In suitable conditions, the spores germinate and grow to form new individuals

Potatoes

• Potatoes are stem tubers
• The parent plant photosynthesizes and stores the food produced in underground stems, which swell to form tubers
• Each tuber contains stored starch, and there are buds in depressions in the surface known as eyes
• In suitable conditions, the buds use the stored food to form shoots, from which roots also develop
• Each tuber can form a new plant

The Advantages and Disadvantages of Asexual Reproduction

Sexual Reproduction

• Sexual reproduction is a process involving the fusion of the nuclei of two gametes (sex cells) to form a zygote and the production of offspring that are genetically different from each other
• Fertilization is the fusion of gamete nuclei
• Nuclei of gametes are haploid and the nucleus of a zygote is diploid

The Advantages and Disadvantages of Sexual Reproduction

Sexual Reproduction in Plants

• Reproduction in flowering plants may occur both sexually or asexually
• Self-pollination is the transfer of pollen grains from the anther of a flower to the stigma of the same flower or different flower on the same plant
• Cross-pollination is the transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species
• Fertilization occurs when a pollen nucleus fuses with a nucleus in an ovule

Parts of a Flowering Plant (Photo Credit: Homestratosphere.com)

Pollen Grains

• Wind-pollinated Flowers
  • Pollen grains are smooth, light and very small to be easily carried by the wind
  • They are produced in large quantities
• Insect-pollinated Flowers
  • Pollen grains are big, and with hooks to attach to insects’ legs
  • They are produces in smaller quantities

Growth of Pollen Tube

• Pollen grain germinates and grows pollen tube
• Pollen tube grows down style
• It secretes enzymes to digest a pathway through the style
• Ovule is surrounded by layers of integuments, at one end, there is a small hole called micropyle
• Pollen tube grows throughout the micropyle and reaches the ovule
• Tip of pollen tube breaks open
• Male gametes travel down the pollen tube and enter the ovule
• Male gametes fuse with female gamete and zygote is formed

Structural Adaptations of Insect-pollinated and Wind-pollinated Flowers

Environmental Conditions Affecting Germination

• Water
  • Absorbed through the microphyle, needed to activate enzymes for converting insoluble food stores into soluble food for growth and energy production
• Oxygen
  • Needed for respiration, to release energy for growth and chemical changes for mobilization of food reserves
• Warmth/Temperature
  • Enzymes present in the seed get activated and work best at optimum temperature (20 – 40°C)
• Light Intensity
  • High or very low light intensity does not allow enzymes to function normally

Sexual Reproduction in Humans

Male Reproductive System

• Testes: Produce sperm and testosterone
• Scrotum: A sac that keeps testes cool (its outside the body)
• Sperm Ducts: Link testes to urethra, allows passage of semen containing sperm
• Prostrate Gland: Produce alkaline fluid (semen)
• Urethra: To urinate, pass semen (+ sperm) through penis
• Penis: Becomes firm, inserted into the vagina during sexual intercourse (to transfer sperm)

Male Reproductive System (Photo Credit: True.org)

Female Reproductive System

• Ovaries: Contain follicles, produce and store eggs, produce estrogen
• Oviducts: Carries ovum to uterus. Fallopian tubes = site of fertilization
• Uterus: Where the fetus develops
• Cervix: A ring of muscles that separate the vagina from the uterus
• Vagina: Receives sperm from an erect penis during intercourse

Female Reproductive System (Photo Credit: True.org)

Adaptive Features of Sperm

• Tail (for motility) which propels it through the cervix, uterus, and Fallopian tube towards the egg
• Each sperm has many mitochondria to release the energy needed for its journey
• Acrosomes allow them to break through the cell membrane of the egg

Adaptive Features of Egg Cells

• It has a large cytoplasm which contains the nutrients and mitochondria needed for mitosis after fertilization
• Each egg has a special cell membrane which only allows one sperm to fertilize it

Fertilization

• When the sperm and egg nucleus fuse together, they form a zygote
• The zygote continues to move slowly down the oviduct
• As it goes, it divides by mitosis
• After several hours, it has formed a ball of cells called embryo
• It takes several hours for the embryo to reach the uterus and by this time it will be a ball of 16 or 32 cells
• The uterus has a thin spongy lining, and the embryo sinks into it
• This is called implantation

Functions of the Umbilical Cord, Placenta, Amniotic Sac, and Amniotic Fluid

• Umbilical Cord
  • Transports nutrients/excretory products
  • Attaches th placenta to the fetus
• Placenta
  • Prevention of material and fetal blood mixing
  • Protection against mother’s immune system
  • Supply of oxygen to fetus
  • Loss of carbon-dioxide from fetus
  • Loss of urea/waste
  • Protection against pathogens
  • Transfer of antibodies
  • Supply of nutrients
  • Secretes hormones
• Amniotic Fluid
  • Support fetus
  • Protects against damage
  • Provides constant temperature
  • Allows fetus to move
  • Needed for bone/muscle growth/development
  • Helps lungs/gut development
• Amniotic Sac
  • Membrane from embryo cells; encloses fetus
  • Prevents entry of pathogens
  • Secretes the amniotic fluid

The Growth and Development of the Fetus

Photo Credit: Dummies.com

• The blastula develops into an embryo and some of the cells form a placenta, linking the embryo with the uterus lining
• Organs such as the heart develop, and after 8 weeks, the embryo is called a fetus
• Some toxins, e.g. nicotine, and pathogens, e.g. rubella virus, can pass across the placenta and affect the fetus

Antenatal Care

•  Antenatal (before birth) care is a routine care for the healthy pregnant woman

Dietary Needs

• Before the baby is born, it obtains all its dietary requirements from its mother through the placenta
• The mother’s diet needs to be balanced so that the fetus receives all the materials needed for healthy growth and development
• If the mother’s diet is deficient in any nutrients, the baby may not develop properly, so her diet should contain plenty of:
  • amino acids: healthy growth and development
  • calcium: development of the skeleton
  • iron: red blood cell formation
  • energy (carbohydrates/fats): help to move mother’s heavier body

Exercise

• Gentle exercise (swimming, walking, etc.)
• Special exercises

Things to Avoid

• Drugs: aspirin, heroin
• Smoking: Nicotine and CO
• Alcohol drinking
• Viruses: HIV, rubella (can pass across the placenta, risking the fetus health)

The Advantages and Disadvantages of Breast-feeding Compared with Bottle-feeding using Formula

The Processes involved in Labor and Birth

Photo Credit: MicrobeNotes.com

• Stage 1
  • The muscular walls of the uterus start to contract slowly stretch the opening of the cervix
  • The pressure breaks the amniotic sac, releasing the amniotic fluid
  • Contraction gradually becomes more frequent, pushing the baby down towards the cervix, which become dilated to allow baby to pass through
• Stage 2
  • The vagina stretches to allow the baby to be born
• Stage 3
  • The baby is still attached to the placenta by the umbilical cord, so this is cut and tied
  • The placenta breaks away from the wall of the uterus and passed out (afterbirth)

Sex Hormones in Humans

• Sex hormones are responsible for the development of secondary sexual characteristics at puberty
• Testosterone is secreted by the testes in males
• Estrogen is secreted by the ovaries in females
• The sex organs become mature and start to secret hormones, making gametes (ova and sperm). This happens at about 10 -14 years

Secondary Sexual Characteristics at Puberty

Sited of Production of Estrogen and Progesterone during the Menstrual Cycle and in Pregnancy

The Menstrual Cycle

• The menstrual cycle in women is a recurring process in which the lining of the uterus is prepared for pregnancy, and if pregnancy does not happen, the lining is shed at menstruation
• The cycle last about 28 days

The Role of Hormones in Controlling the Menstrual Cycle and Pregnancy

Methods of Birth Control in Humans

• There are four main groups of birth control methods: natural, chemical, mechanical, and surgical
• Natural Methods
  
• Chemical Methods
  
• Mechanical Methods
  
• Surgical Methods
  

The Use of Hormones in Contraception and Fertility Treatments

• Fertility drugs are used when the woman is not producing enough eggs
• She is given hormones, including FSH, and LH, that cause multiple release of eggs

Artificial Insemination (AI)

• An artificial insemination procedure uses a thin, flexible tube (catheter) to put sperm into the woman’s reproductive tract (vagina, cervix, and uterus) around the time of ovulation
• For some couples with infertility problems, insemination can improve the chances of pregnancy

In Vitro Fertilization

• If the woman has a problem with blocked oviducts, the eggs are removed from her ovaries just before they are due to be released, and placed in a warm liquid in a Petri dish.
• Some of her partner’s sperms are added, and fertilization takes place in the dish
• Two or three of the resulting zygotes are placed into her uterus, where they develop in the usual way
• This is called in vitro fertilization

The Social Implications of Contraception and Fertility Treatments

• Fertility
  • Stress is associated with the difficulty of having children
  • Multiple births might occur
  • Problems with unused embryos when used with IVF
  • Issues with elderly parents
  • Religious objections to the use of fertility drugs
  • Treatment might be expensive
  • Can be used to increase population (useful in countries where birth rate is low)
• Contraception
  • It is a widely held belief that the pill revolutionized sex for women as they no longer had to worry about pregnancy
  • It allows for population control in a way that did not exist 100 years ago
  • Religion often forbids the use of contraception

Sexually Transmitted Infections (STIs)

• Sexually transmitted infection is an infection that is transmitted via body fluids through sexual contact
• Human immunodeficiency virus (HIV) is an STI

How the Spread of STIs is Controlled

• Use of condoms during sexual intercourse
• Abstinence from sexual intercourse
• Screening of blood for transfusions
• Use of sterile needles
• Use of sterilized surgical instruments

How HIV Affects the Immune System

• HIV attacks the lymphocytes, so the number of these cells in the body decreases
• Lymphocytes produce antibodies against infections
• If the body cannot respond to infections through the immune system, it becomes vulnerable to pathogens that might not otherwise be life-threatening
• As a result, the patient has little or no resistance to a wide range of diseases such as influenza, pneumonia, blood disorders, skin cancer or damage to the nervous system, which the body cannot resist

The Methods of Transmission of HIV

• Unprotected sexual intercourse
• Across placenta at birth or in breast milk
• Sharing needles
• Blood for transfusion