Triple Science Things I need to Know

How does leafs structure make gas exchange easy

• Large surface area → more space for diffusion.

• Thin → short diffusion distance.

• Air spaces in the spongy mesophyll → gases move freely inside the leaf.

• Stomata → allow gases to diffuse in/out.

• Guard cells → control the opening and closing of stomata.

how is WATER absorbed by root hair cells

by osmosis

how does increased humidity DECREASE rate of diffusion

lots of water particles in air so shallow concentration gradient

energy released from food per gram

Q= mass of water x cat/ mass of food sample

how do vaccines work

• once in the blood stream, the antigens contained within the vaccine can trigger an immune response

• Lymphocytes recognises the antigens in the bloodstream

• The activated lymphocytes produce antibodies specific to the antigen encountered

• Memory cells are produced from the lymphocytes

• Memory cells and antibodies remain circulating in the blood stream

what does adh do

• released from pituitary gland in brain

• travels to collecting duct via the blood

• adh causes more aquaporins to attach to the collecting duct wall

• aquaporins reabsorb more water from the nephron 

Biodiversity definition

the total number and variety of different species in a given ecosystem

effects of deforestation

• leaching → soil minerals are not taken up by trees and are instead washed away by rain into nearby bodies of water

• soil erosion → soil is not held together by tree roots and organic matter, more likely to be washed or blown away

• carbon → the removal of trees reduces photosynthesis so less carbon removed from atmosphere and stored in plant tissues

Why do metals have a high melting point?

• Has a giant structure

• so there are strong forces of attraction between the delocalised electrons and positive metal ions which require lots of energy to break