Bio

Functions of alimentary canal (mouth à anus): 

• Ingestion = taking in food and drink through mouth into the body 

• Digestion = can be mechanical (physically breaking down large pieces of food into smaller pieces through chewing, grinding in stomach etc) and chemical (break down large molecules into smaller molecules) 

• Absorption = small food molecules and ions move through intestine wall into the blood, only small, soluble substances can pass through the wall of the small intestine. Large insoluble substances cannot pass through. The inside wall of the small intestine needs to be thin, with a big surface area. This allows absorption to happen quickly and efficiently. 

• Assimilation = digested food molecules move into cells where needed 

• Egestion = removing the food that isn’t digested or absorbed as faeces through the anus 

Tooth decay: 

• Fluoride is found in most toothpastes as it is important for reducing tooth decay dental cavities. 

• Negative effects of fluoride = excess fluoride exposure will result in fluorosis (staining of teeth) 

• asexual reproduction is a process resulting in the production of genetically identical offspring from one parent

   

  ·         asexual reproduction advantages:

  -save time and energy (don’t need to find a mate -only require one parent)

  -same gene as parent = same antibodies.

   

  ·         Asexual reproduction disadvantages:

  -no variation. If there are changes in the environment, the organisms will all be affected, less likely to have individuals surviving.

   

  ·         Sexual reproduction advantages:

  -variation between organisms of the same population, negative changes in the environment are less likely to affect the whole population or will take longer to affect everyone.

  ·         Sexual reproduction disadvantages:

  -take longer time and energy as two parents are required.

  -difficult to find mates for species with balanced female to male population.

   

  ·         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

   

  

  ·         functions of the male reproductive systems:

  -testes – production of male gametes (sperm)

   

  -scrotum – sac that holds the testes outside the body

   

  -sperm ducts – transfer sperm to the urethra

   

  -prostate gland – secrete fluids for sperm to  swim in forming semen

   

  -urethra – carries urine and semen out of the body

   

  -penis – transfers semen to vagina during sexual intercourse

   

  

  ·         functions of the female reproductive systems:

  -ovaries – release of female gametes (eggs)

  -oviducts – transfers egg to uterus and the site of fertilisation

  -uterus – where the foetus develops

  -cervix – ring of muscle at the opening of the uterus

  -vagina – receives penis during sexual intercourse

   

  ·         fertilisation is the fusion of the nuclei from a male gamete (sperm) and a female gamete (egg cell/ovum)

   

  ·         Compare male and female gametes in terms of size, structure, motility and numbers

  -sperm cell = very small, mobile with flagellum (tail like structure) for movement, and enzyme in acrosome to break down the membrane of ovum, millions in sperm.

  -ovum =very big cell, immobile (cannot move), only one produced per menstrual cycle.

   

  ·         The menstrual cycle is a hormone regulated cycle.  On average, it lasts 28 – 35 days.

  ·         Menstruation marks the beginning of each cycle, and thus, the first part of the follicular phase. This is when the endometrium lining sheds.

  ·         During menstruation, follicles start to develop, and along with them, the oocytes they carry. The Endometrium lining starts getting repaired.

  ·         Ovulation = dominant follicle bursts and turns into a corpus luteum, and the oocyte is released into the oviduct