SB1a - SB1c Key Concepts In Biology Flashcards
What does magnification of x30 On a microscope mean
It means it makes things 30x bigger
Who used a two lens microscope to discover cells and when
Robert Hooke in 1665
What are the two lenses of a microscope called
Objective lens and eyepiece lens
How do you workout the magnification of a microscope
Eyepiece lens x objective lens
What does the detail obtained by a microscope depend on
The microscopes resolution
Resolution definition
The smallest distance between two points that can still be seen as two points
State three differences between electron and light microscopes
Electron microscopes use beams of electrons to pass through a specimen to build up an image whereas light microscopes use light
Light microscopes are more affordable and will be the first choice for most average people whereas electron microscopes are extremely expensive and are used in high end companies .
Light microscopes can magnify up to x1500 with resolutions down to 0.0001mm whereas electron microscopes can magnify up to x2,000,000 with resolutions down to 0.000,000,2 meaning they allow us to see cells with great detail and clarity .
Who discovered the cells nucleus and when
Robert brown in 1828
What is a cell with a nucleus called
A eukaryotic cell
Cell membrane function
Controls what enters and leaves the cell and separates one cell from another
Cytoplasm function
Contains a watery jelly where most of the cells activities occur
Nucleus function
It Controls the cell and its activities . In it are chromosomes which contain DNA. It is especially large in white blood cells
What are ribosomes
Tiny round structures found In the cytoplasm that make new proteins for a cell . They are impossible to see with a light microscope . They are impossible to see with a light microscope
What are mitochondria
Jelly bean shaped structures which provide energy to the cell . They are difficult to see with a light microscope
What are the additional structures plant cells have and their function
Vacuole - stores cell Sap and helps to keep the cell firm
Cell wall - made of cellulose and supports and protects the cell
Chloroplasts - contain chlorophyll which traps energy transferred from the sun , this energy is then used for photosynthesis
What are specialised cells
Specialised cells are cells adapted to their function
Explain how a cell can be adapted for digestion
The cells that line the small intestine which are their to absorb small food molecules produces by digestion are adapted by having membranes with a lot of tiny folds called microvilli . This increases the surface area of the small intestine . The more area for molecules to be absorbed , the faster absorption happens .
How are cells in the pancreas adapted and why
Cells in the pancreas make enzymes needed to digest certain foods. These enzymes are proteins and so the cells the make them are adapted by having a lot of ribosomes.
Sexual reproduction in simple terms
When two specialised cells ( gametes ) fuse to create a cell that develops into an embryo
Sexual reproduction simple terms
When two male and female gametes fuse to create a cell that develops into an embryo
How many chromosomes does a human cell have vs a gamete cell
Human cell has 23 pairs of chromosomes ( 46 in total )
Gamete cell has only 23
What is a diploid cell
Cells with two set of chromosomes
What is a haploid cell
Cell with one copy of each chromosome
State and explain the adaptations of a human female gamete
- haploid nucleus
- cytoplasm is packed with nutrients to supply the egg cell with energy and raw materials for the growth and development of the embryo
- After fertilisation the cell membrane becomes hard to stop other sperm from entering
- jelly coat surrounding the cell membrane to protect the egg cell . The jelly coat also harder so after fertilisation to stop other sperm from entering
