3a Reproduction Flashcards
What is sexual reproduction?
- Usually 2 parents gametes are involved
- Get some variations
- Is the production of new individuals by fusion of male and female gametes
What is asexual reproduction?
- No gametes involved
- No sex cells involved
- Only one parent
- Cloning
- The production of new individuals without fertilisation from division of body cells in the parent
Sexual reproduction (summer)
- Involves the joining (fusion) of male and female gametes (sex cells)
- Genes from two parents
- Offspring show variation
- Relatively slow process as a mate has to be found
Asexual reproduction (summery)
- No fusion of gametes (sex cells)
- Genes from only one parent
- Offspring show NO variation
- Genetically identical offspring (clones)
What are some examples of asexual reproduction?
- Binary fission in bacteria
- Taking plant cuttings
- Cloning
- Runners in plants eg. strawberry plants
Some of these methods of asexual reproduction are natural and some are artificial. All offspring from asexual reproduction are clones of the parent. They have identical DNA to the parent
How do you clone a plant?
Taking Cuttings
- Whenever you “clip” off a piece of a plant and put it to grow in new soil you are making a clone of the plant
- The new plant is identical to the plant that you took the clipping from
- This is because plants grow by asexual reproduction
What are gametes and where are they formed?
- Gametes are sex cells
- They are formed in special sex organs called gonads
What is the male gamete and where is it produced?
- The male gamete is called a sperm cell and are produced in the male gonads called the testes
What is the female gamete and where is it produced?
- The female gamete is called ova (more commonly known as egg) and are produced in the female gonads called the ovaries
What is the function of the oviduct (Fallopian tube)?
- the tube through which the ovum moves from the ovary to the uterus
What is the function of the uterus?
- The embryo develops here
What is the function of the ovaries?
- This produces the ova (eggs)
What is the function of the cervix?
- The opening from the vagina to the uterus
What is the function of the prostate gland + seminal vesicle?
- Secretes a fluid that mixes with the sperm to produce semen
What is the function of the testes?
- This is where sperm are produced
What is the function of the sperm duct?
- These tubes carry sperm from the testes to the urethra
What is the function of the scrotum?
- The sac that contains the testes
What is fertillisation?
- Fertilisation is when the nucleus of the ovum (female sex cell) fuses with the nucleus of the sperm (male sex cell)
- the fusion of female and male gametes to form a new cell called a zygote
What is the order in which an egg is fertillised?
1 - Sperm are produced by the testes
2 - During intercourse they pass along the sperm duct (vas deferens)
3 - They mix with the fluid from the seminal vesicles and prostate gland
4 - The mixture is now called semen
5- It is ejaculated into the vagina of the female
6 - The sperm swims through the cervix
7- The sperm swims towards the Fallopian tube to fertilise an ova
How many chromosomes does a gamete and zygote have?
- Each gamete has half of the number of chromosomes (haploid)
- Zygote formed by fertillisation has the full number of chromosomes (diploid)
What are primary sex characteristics?
- Refer to the changes that occur during puberty to the sexual organs
What are some examples of primary sex characteristics?
- Uterus
- Vagina
- Penis
- Testes
What are secondary sec characteristics?
- Refer to visible, physical changes that mark adult maturation. They make it clear that the body is now mature enough for reproduction
What are some examples of secondary sex characteristics?
- Body hair
- Hips widening
- Breasts start to form
-Voice deepens - Growth spurt
What is the menstrual cycle?
- The menstrual cycle is one of the secondary sexual characteristics that starts in early adolescence in females (around age 12)
- The average menstrual cycle is 28 days long
- Ovulation occurs around day 14, with the egg travelling to the uterus
- If the egg is not fertilised, menstruation (period) begins due to the breakdown of the uterine lining
- Menstruation lasts around 5 - 7 days and signals the beginning of the next cycle
- After menstruation finishes, the lining of the uterus starts to thicken again in preparation for possible implantation in the next cycle
What are the 4 main hormones that the menstrual cycle is controlled by?
- Oestrogen
- Progesterone
- FSH (Follicle stimulating hormone)
- LH (Luteinising hormone)
Where are all the hormones secreted from?
Oestrogen and Progesterone - Secreted from cells in the ovaries
FSH and LH - Secreted from the pituitary gland in the brain
What is the role of oestrogen in the menstrual cycle?
- Repairs the lining of the uterus after menstruation
- Released - day 7-13
What is the role of progesterone in the menstrual cycle?
- Completes the development of the uterine lining and maintains it
- Increased in production - day 14-23
What is the role of FSH in the menstrual cycle?
- It causes an egg to mature in an ovary
- It stimulates the ovaries to release the hormone oestrogen
- Released - start of the cycle
What is the role of LH in the menstrual cycle?
- Causes the mature egg to be released from the ovary
- Level of LH peaks - Day 14
What changes happen to a developing embryo and a foetus?
- Growth
- Excretion
- Cell division
- Respiration
- Differentiation of cells to produce tissue organs and systems
What is the role of the placenta?
- The placenta is responsible for providing oxygen and nutrients (glucose and amino acids) and removing waste substances
What is the role of the amniotic fluid?
- The foetus is protected by the uterus and the amniotic fluid, a liquid contained in a bag called the amnion
- Regulates temperature and acts as a shock absorber
