CB1: Key Concepts in Biology Flashcards
Define Magnification
The ability to enlarge smaller object’s appearance
What is the formula to calculate magnification using the two lenses?
eyepiece lens x objective lens
How do you calculate magnification based off of image size?
magnification = image size/ actual size
Define resolution
How detailed an image is
What is the difference between a light microscope and an electron microscope?
A light microscope uses light to display enlarged images and has a lower resolution as compared to an electron microscope. An electron microscope uses electrons to display images and has a higher resolving power than the light microscope
What is the limitation of an electron microscope?
You can’t observe living things because samples are placed in vacuums
What is the difference between a prokaryotic and eukaryotic cell?
Eukaryotic cells: cells with a nucleus eg: animal and plant cells
Prokaryotic cells: cells without a nucleus eg: bacteria
What is the role of the nucleus?
- controls the cell and its activities
- contains chromosomes
What is the role of the cell membrane?
- thin bag
- controls what enters and leaves
What is the role of the mitochondria?
Where aerobic respiration occurs
What is the role of the ribosomes?
Makes proteins for the cells
What is the role of the chloroplasts?
- contain chlorophyll
- traps energy from the sun to be used in photosynthesis
What is the role of the cell wall?
- made of cellulose
- supports and protects the cell
What is the role of the vacuole?
- stores cell sap
- helps keep the cell rigid and firm
Define specialised cells
Cells with specific functions/ jobs
What are the adaptations of an egg cell?
- haploid for fertilisation to make a diploid cell
- jelly coat protects the egg and hardens after fertilisation to prevent other sperm cells from entering
- cell membrane: fuses with the sperm cell membrane. also hardens after fertilisation to prevent other sperm cells from entering
- cytoplasm: packed with nutrients to supply fertilised egg cell with energy and raw materials for growth and development of embryo
What are the adaptations of a sperm cell?
- haploid
- streamlined shape: helps it to swim faster
- lots of mitochondria: releases lots of energy
- tail to move
- acrosome: contains enzymes that break down substances in the jelly coat of the egg
What are the adaptations of ciliated epithelial cells?
- cilia covered in cell membrane
- contains strands of a substance that can contract and cause wavy movement
What is the role of the chromosomal DNA?
- controls cells activities
- found free in the cytoplasm
What is the role of the plasmids?
- controls some of the cell’s activities
- extra DNA
What is the role of the flagellum?
- long thin ‘whip-like’ tails
- so bacteria can move
Define enzymes
Biological catalysts
What is the role of an enzyme?
It can break down large substances into small ones (breakdown) and join small substances into larger ones (synthesis)
What does protein break down into?
Amino acids
What does starch break down into?
Glucose
What do lipids break down into?
Fatty acids and glycerol
What is the active site of an enzyme?
The part of the enzyme where the substrate fits into
Explain the lock and key hypothesis
The shape of the active site matches the shape of its substrate, which forms an enzyme-substrate complex. Once bound, the reaction takes place on the enzymes surface.
What happens when an enzyme becomes ‘denatured’?
The shape of the active site changes, so the substrate no longer fits in it
What three conditions affect enzyme activity?
- temperature
- pH
- substrate concentration
What occurs to an enzyme when we pass its optimum temperature/ pH?
It becomes denatured
What occurs to an enzyme when we pass its optimum substrate concentration?
All the enzymes become saturated, so increasing the substrate concentration after this point will have no affect on the enzymes themselves.
How do we calculate rate?
change in measured substance / time it takes for change to be displayed
Define diffusion
When particles move from an higher concentration to a lower concentration. It doesn’t require energy
Define osmosis
The diffusion of solvents through a partially permeable membrane. It doesn’t require energy
Define active transport
When cells transport molecules against a concentration gradient/ transport those that can’t fit through the partially permeable membrane. This requires energy
How do you calculate the percentage change in mass?
((final mass - initial mass)/initial mass) x 100
What enzyme causes the breakdown of carbohydrates?
Carbohydrases
What enzyme causes the breakdown of proteins?
Protease
What enzyme causes the breakdown of lipids?
Lipases
What is a hypotonic solution?
More water than sugar
What is an isotonic solution?
Equal amounts of water and sugar
What is a hypertonic solution?
More sugar than water
What is the difference between animal cells and plant cells in a hypotonic solution?
Animal cell: Lysed (cell membrane is broken or destroyed)
Plant cell: Turgid (tissues swollen by water uptake) normal
What is the difference between animal cells and plant cells in an isotonic solution?
Animal cell: normal
Plant cell: flaccid (drooping/inelastic due to lack of water)
What is the difference between animal cells and plant cells in a hypotonic solution?
Animal cell: shrivelled
Plant cell: plasmolysed (shrinking of the cytoplasm from the wall of the living cell due to the lack of water)
