Biology TA2

• How do smoking and alcohol affect unborn babies?

  • Carbon monoxide from tobacco smoke reduces the amount of oxygen the foetus receives, which can lead to premature death or stillbirth
  • Alcohol passes across the placenta and damages the developing foetus. Once born, the baby may have a number of deformities and health problems as part of foetal alcohol syndrome
• How do carcinogens affect the development of cancer? 


  Ionising radiation is a type of carcinogen which can cause mutations in DNA, potentially leading to cancer
• What is cancer? 


  Cancer is the development of a tumour as a result of uncontrolled cell division
• What is a benign tumour?

  • A tumour that is contained in one location, usually within a membrane
  • They are not cancerous and do not invade other parts of the body
  • Can grow large very quickly - may cause damage to another organ
• What is a malignant tumour?

  • A tumour that can spread around the body via the blood and lymphatic system
  • Can invade other tissues
  • Cells divide more rapidly and have longer lifespan
  • Disrupts healthy tissues and may lead to death
• Give examples of factors which can lead to cancer

  • Genetics - certain genes increase risk of breast and ovarian cancer
  • Smoking
  • Obesity
  • Ionising radiation - UV light and X-rays
  • Viral infections - HPV and cervical cancer
• How can life situations affect health? 


  Many life factors such as location, gender, financial status, ethnic group and healthcare provision can impact a persons mental and physical health
• Give examples of how health problems can interact

  • Infection with certain viruses can lead to cancer
  • A compromised immune system can lead to a higher risk of infection with communicable diseases
  • Immune reaction caused by a pathogen can trigger allergic reactions
  • Problems with physical health can lead to mental health issues
• What is a risk factor?

  An aspect of a persons lifestyle or a substance found in the body or the environment which can increase the risk of a disease
• What is a causal mechanism?

  A mechanism which demonstrates how one factor biologically influences another
• How do diet, smoking and exercise affect the development of cardiovascular disease?

  • Diet: high levels of LDL cholesterol causes arteries to become blocked, increasing blood pressure and the risk of a heart attack
  • Smoking: nicotine increases heart rate; other chemicals damage the artery lining and increase blood pressure
  • Exercise: lowers blood pressure, reducing strain on the heart
• How does obesity affect the development of type 2 diabetes? 


  Obesity is strongly linked with the onset of type 2 diabetes- a disease in which the body stops responding to insulin
• How does alcohol affect liver and brain function?

  • excessive long-term alcohol use may lead to liver cirrhosis (scarring of the liver)
  • increases risk of liver cancer
  • damages brain tissue and nerve cells
• How does smoking affect the development of lung disease and lung cancer?

  • tar in tobacco can damage the alveoli of the lungs, leading to chronic obstructive pulmonary disease (COPD)
  • tar also damages the cells which line the lungs, leading to lung cancer
• How are stomata adapted for their function? 


  stomata allow the control of gaseous exchange and water loss from the leaf

  • more stomata on the base of the leaf - minimises water loss as this side is cooler and shaded
  • have guard cells which control their opening and closing
• How are root hair cells adapted for their function? 


  Root hair cells allow the uptake of water and mineral ions from the soil

  • large surface area - maximises rate of absorption
  • contains lots of mitochondria - releases energy for active transport of mineral ions
• What is translocation?

  Translocation is the movement of dissolved sugars from the leaves to other parts of the plant
• What is transpiration?


  Transpiration is the evaporation of water vapour from the surface of the plant
• How does transpiration work?

  • water evaporates from the leaf surface via the stomata
  • water molecules cohere together - more water is pulled up the xylem in an unbroken column
  • more water is taken up from the soil - creating a continuous transpiration system
• How does temperature affect the rate of transpiration?

  Increasing the temperature increases the rate of transpiration

  • Higher rate of evaporation and diffusion of water - therefore rate of transpiration is increased
• How does humidity affect the rate of transpiration? 


  Increasing relative humidity decrease the rate of transpiration

  • High relative humidity will reduce the water vapour concentration gradient - the rate of evaporation will decrease and so will the rate of transpiration
• How does wind speed affect the rate of transpiration?

  Increasing wind speed/air movement increases the rate of transpiration

  • Increased air movement lowers water vapour concentration outside the leaf - this increases the water vapour concentration gradient, therefore increasing the rate of evaporation and transpiration
• How is epidermal tissue adapted for its function?

  Epidermal tissues covers the entire plant. It has a waxy cuticle which helps reduce water loss from the leaf surface
• How is palisade mesophyll tissue adapted for its function?

  Palisade mesophyll tissue contains lots of chloroplasts which allows photosynthesis to progress at a rapid rate
• How is spongy mesophyll tissue adapted for its function?

  Spongy mesophyll tissue has lots of air spaces which allow gases to diffuse in and out
• How is the xylem adapted for its function?

  • Made up of dead cells which form a continuous hollow tube - allows the movement of water and mineral ions from the roots to the leaves
  • Strengthened by lignin - makes the vessel strong and waterproof
  • Has bordered pits - allow minerals to be transported to specific places
• How is phloem adapted for its function?

  • Made up of elongated living cells
  • Cells have sieve plates that connect them together - cell sap can move through plates into other cells
  • Sieve tube cells have few organelles to allow the efficient transport of substances
• How is meristem tissue adapted for its function? 


  Made up of stem cells which can differentiate into many different cell types, allowing the plant to grow
• What tissues does the leaf organ contain?

  • epidermis
  • palisade mesophyll
  • spongy mesophyll
  • xylem
  • phloem
  • guard cells
• What is the function of guard cells?

  Guard cells control the opening and closing of the stomata, according to the water content of the plant
• What is a cell?

  The basic building block of a living organism
• What is a tissue?

  A group of cells with a similar structure and function working together
• What is an organ?

  A collection of tissues working together to perform a specific function
• What is an organ system?

  A group of organs working together to perform specific functions
• Pathway of blood through heart


  1. Deoxygenated blood enters the heart via the vena cava, emptying into the right atrium

  2. Blood flows down through a set of atrioventricular valves into the right ventricle

  3. When the ventricles contract, blood travels up through the pulmonary artery to the nearby lungs where gas exchange occurs (and the blood becomes oxygenated)

  4. Oxygenated blood returns to the heart via the pulmonary vein, emptying into the left atrium

  5. Blood flows down through a set of atrioventricular valves into the left ventricle

  6. When the ventricles contract, blood travels up through the aorta, and to the rest of the body