Natural Science Grade 9

• What is a microscope?

  A microscope is an instrument that contains one or more magnifying lenses.
• Name a type of Microscope


  The compund light microscope.
• Label the parts of a microscope

  Parts

  A) ocular lens/eyepiece

  B) Body tube

  C) Rotating nose piece

  D) Objective lenses

  E) Stage/platform

  F) Diaphragm and condenser

  G) Light source / mirror

  H) Arm

  I) fine focusing knob

  J) base

  K) Coarse focusing knob

  
• Name the respective magnification settings of the objective lenses

  x4 (low)

  x10 (medium)

  x40 (high)
• State the function of the ocular lens/eyepiece

  The ocular lens is closest to your eye because you can look through it at about 10x magnification
• State the function of the body tube

  The body tube contains the lenses that magnify the object
• State the function of the rotating nosepiece 


  The rotating nose piece is a structure that turns to allow 1 of the 3 objective lenses to be used to view a specimen
• State the function of the 3 objective lenses.


  The three objective lenses are closest to the specimen, usually attached to the rotating nosepiece
• State the function of the stage/platform 


  A stage is where the slide is placed and has clips to hold the slide in place
• Explain the function of the Diaphragm and Condenser 


  The Diaphragm adjusts the amount of light that passes through the specimen. The Condenser focuses or concentrates the light onto the specimen
• Explain the function of a light source


  The light source produces or directs light onto the specimen
• State the function of the arm

  The arm connects the body tube to the base and is used to carry the microscope
• State the function of the Coarse focusing knob


  You are able to turn the knob which changes the distance between the stage and objective lens quickly to place the specimen into the rough objective
• Explain the fine focusing knob 


  Turning the knob changes the distance between the stage and objective lens slowly allowing a clear focus onto the specimen.
• Explain the funtion of the base 


  The base supports the lenses and stage .Also used to carry the microscope
• Label the plant cell

  Label

  A) cytoplasm

  B) chloroplasts

  C) mitochondria

  D) vacuole

  E) nucleus

  F) cell membrane

  G) cell wall

  
• Label the animal cell

  Label

  A) cell membrane

  B) nucleus

  C) mitochondria

  D) vacuole

  E) cytoplasm

  
• Explain cells 


  cells form tissue eg. skin

  Tissue forms organs eg .hearts

  Organs form a organ system eg. respiratory system
• Explain Stem cells


  Cells that have not yet been developed and can specialise into any cell in the human body

  Researchers often conduct research on stem cells but to do this stem cells must be harvested/ collected

  Stem cells can be harvested through blood, adipose, tissue, fat tissue, bone marrow, and the human embryo

  This harvesting of stem cells from the human embryo is often seen as ethically and morally wrong as it is seen as destroying a human life
• What is digestion 


  The mechanical and chemical process that converts insoluble foods into soluble nutrients
• What is the function of digestion?

  The digestive system breaks down food into smaller pieces so that the nutrients from the food can be absorbed into the bloodstream and transported to the cells where they can be used.The nutrient glucose nourishes the body
• Label the digestive system

  Label

  A) salivary glands

  B) mouth

  C) oesophagus

  D) stomach

  E) pancreas

  F) small intestine

  G) rectum

  H) anus

  I) large intestine

  J) liver

  K) gall bladder

  
• explain the function of the mouth in the digestive system

  Ingestion takes place. Ingestion is the intake of food by biting, chewing, mechanical digestion, and swallowing. The tongue helps to mix food with the saliva. Enzymes (Proteins that speed up reactions)breakdown starch in the mouth
• Explain the oesophagus in the digestive system

  Muscles contract, peristelsis pushes food along the oesophagus
• Explain the stomach in the digestive system

  The stomach has thick muscular walls that contract and churn, breaking up food further into smaller parts. Secretes hydrochloric acid and enzymes to speed up the chemical reaction of breaking down food called chyme
• Explain the small intestine in the digestive system

  Food is digested and lined with villi that absorbs nutrients
• Explain the large intestine in the digestive system

  Absorbs water from the waste into the bloodstream.Compacts the waste into faeces. Stores the waste before getting egested
• Explain the liver in the digestive system 


  Breaks down substances to form bile. Bile is stored in the gall bladder
• Explain the rectum in the digestive system

  Temporarily stores waste as faeces.
• Explain the anus in the digestive system

  Waste is egested. Egestion: undigested waste gets passed out the body
• What is mechanical digestion and what is it helped by

  Mechanical digestion is the physical breakdown of food by crushing, chewing and churning.Large food particles are broken down into smaller particles and it is helped by the mouth - teeth for crushing, tongue for pushing food down and stomach muscles help with churning and mixing
• What is chemical digestion and what is it helped by

  Chemical digestion is the the breakdown of food into nutrients by means of chemical reactions it is helped by the salivary glands. Saliva enzymes to break down food into starch. HCI secreted by the stomach . Enzymes in the stomach and small intestine
• What is absorption and what is it helped by

  Absorption is when soluble nutrients are taken into the blood. It is helped by millions of villi-villi contain blood vessels which absorb nutrients and those nutrients are transported via the bloodstream to body cells
• Ulcers


  Breaks in the skin or the mucous membrane of the mouth, stomach or intestines that do not heal easily on their own, caused by bacteria
• Anorexia


  An eating disorder that causes people to obsess about food or gaining weight. People may starve themselves or exercise excessively
• Diarrhoea


  Person has 5+ bowel movements/watery stool per day, caused by drinking bacteria-contaminated water
• Liver Cirrhosis


  A disease of the liver when liver tissue is replaced by abnormal nodules or connective tissue, caused by drinking too much alcohol
• Name the three kind of blood vessels

  arteries, veins, capillaries
• What are arteries 


  blood vessels that transports blood away from the heart
• What are veins


  Blood vessels transporting blood towards the hearts