biology summer exam

• what is a cell


  Building blocks / basic structures of an organism
• how do you use a microscope to observe a cell

  1 Move stage to its lowest position , 2 Place object to be observed on stage , 3 Select the lowest magnification objective lens , 4 Look through eyepice and turn coarse-focus knob until object can be seen , 5 Turn fine-focus knob until object comes into focus , 6 Repeat stages 1-5 with higher magnification
• how to prepare a slide


  use tweezers to place specimen on microscope slide , place fluid over the specimen and cover with cover slip
• similarities between animal and plant cells


  Both have cell membrane , nucleus , mitochondria and cytoplasm
• differences between animal and plant cells


  Animal has more irregular structure , plant more regular shape , plant has three extra components cell wall , vacuole and chloroplast
• nucleus


  control centre of cell , contains genetic material which is passed from parent to offspring
• cytoplasm


  jellylike substance , where chemical reactions needed for life take place, e.g releasing energy by respiration and making new substances
• cell membrane


  barrier around the cell , controls what comes in and out
• mitochondria


  where respiration happens , transfers energy to cell/organism
• cell wall


  strengthens and provides support to the cell , made of a fibre called cellulose which makes the wall rigid , helps keep the cell's shape
• chloroplasts


  Where photosynthesis happens , contains a green pigment ,chlorophyll, which traps energy from sun
• vacuole


  Contains watery liquid called cell sap , keeps cell firm
• examples of specialised animal cells 


  Red blood cells , sperm cells , muscle cells and nerve cells
• examples of specialised plant cells

  root hair cells
• structural adaptations of animal cells


  Nucleus , cell membrane , mitochondria and cytoplasm
• structural adaptations of plant cells

  Nucleus , cell membrane , mitochondria , cytoplasm , chloroplasts , cell wall and vacuole
• adolescence

  a time where you change from child to adult
• puberty

  the physical changes that occur during adolescence
• changes in female bodies during puberty


  periods start , breasts develop , hips develop , ovaries start to release egg cells , pubic hair grows , produce sex hormones , body odour and grow acne
• changes in male bodies during puberty


  voice breaks , shoulders widen , testes start to produce sperm , body gets more muscular , teste and penis gets bigger , make sex hormones , hair grows around genitals , face , legs , chest and arms , produce body odour and grow acne
• Bladder


  Stores waste from your blood and urine until ready to be emptied
• Gland


  Produces seminal fluid which helps transport sperm out of the man's body, the two combined are called semen
• Sperm duct


  Transports sperm from the testes to the urethra/penis
• Penis


  Organ used for urination and sexual intercourse, inserts sperm into the female
• Urethra


  Allows semen and urine to pass through the penis
• Testicle or testes


  2 small organs that produce sperm and the male hormone testosterone
• Scrotum


  A bag of skin that holds and protects the testicles, keeps the testes around 2-3 degree lower than the body temperature to ensure the quality and production of the sperm
• Gametes


  Sex cells called sperm which are produced in the testes
• Main structures of the male reproductive system


  • Bladder
  • Gland
  • Sperm duct
  • Penis
  • Urethra
  • Testicle or testes
  • Scrotum
  • Gametes
• what is meant by a person being infertile

  when they have difficulty having a baby , reasons -> men = low sperm count or sperm that does not swim properly or female = egg cells not released monthly or fallopian tubes blocked
• fertilisation 


  when a sperm cell and an egg cell meet in the fallopian tubes / oviduct
• what happens if an egg is fertilised


  it settles into the uterus lining
• gestation 


  the time in the uterus from fertilisation until birth
• how long does a pregnancy last

  9 months or 40 weeks in a human
• the sequence of events during gestation

  when the egg becomes fertilised it forms a zygote and it divides so the number of cells double each time which allow the zygote to grow into an embryo , the cells in the embryo specialise and divide to form a foetus after eight weeks of growth
• the other sequence of events during gestation

  1 week - a dot , cells beginning to divide and specialise , 4 weeks - 3mm long , spine and brain forming , heart beating , 9 weeks - 3 cm long , tiny movements , lips and cheeks sense touch , eyes and ears start forming , 12 weeks - 7 cm long , foetus uses its muscles to kick , suck , swallow and practise breathing
• how do contractions bring about birth


  they open your cervix by relaxing it and the muscles in the wall of the uterus contract , which moves the baby down the baby out of the vagina
• what is the effect of cigarettes on a developing foetus

  carbon monoxide in cigarette smokes reduces the amount of oxygen that reaches the baby so it can not grow properly and may be underweight
• what is the effect of drugs on a developing foetus

  increases the risk they will be stillborn or will die in the first few weeks or months of life , increases risk of behavioural problems , miscarriage and birth defects
• what is the effect of alcohol on a developing foetus

  forms the risk of miscarriage , premature birth , long term damage to the baby , large amounts of alcohol can cause foetal alcohol syndrome which leads to poor growth , facial abnormalities , learning and behaviour difficulties