Biology Sem 2 Stage 1 Exam

Simple diffusion

• moves with the concentration gradient

• Molecules keep moving until equillibrium

• Passive transport

Facilitated Diffusion

• move with the concentration gradient

• for larger molecules such as ions, water and glucose

• uses protein channels

Factors affecting rate of diffusion

• distance

• temperature (higher temp. = increased rate of diffusion)

• characteristic of solute (mass)

• density of solent (jelly or water)

• characeristic of barrier (cell membrane)

osmosis

• passive transport

• goes with concentration gradient

  • from low solute concentration to high solute concentration

• movement of water through semi-permeable membrane

hypertonic

high solute, low water

water moves out of cell

plants - plasmolysed

animals - shriveled

hypotonic

low solute, high water

water moves in to cell

plants - turgid (normal)

animals - lysed

isotonic

conc. of water = conc. of solute

plants - flaccid

animals - normal

passive transport

• no energy

active transport

• requires energy

• uses carrier proteins that open and close using ATP

Aerobic respiration

• uses oxygen

• produces 36 - 38 molecules of atp

oxygen + glucose —> water + carbon dioxide + ATP

Anaerobic respiration

• without the presence of oxygen

• fermentation

• produces 2 molecules of ATP

In plants:

glucose —> ethanol + carbon dioxide + ATP

In animals:

glucose —> lactic acid + ATP

glycolysis

• happens in both anaerobic and aerobic

• occurs in cytoplasm

• braking of glucose into 2 pyruvate molecules

• Glycolysis needs 2 ATP molecules to work

• At the end of the process, it produces 4 ATP

• Therefore profit of 2 ATP

Krebs cycle (aerobic)

• produces two ATP from the two pyruvates

• Also produces 2 NADH

• occurs in mitochondria

Electron transport chain (aerobic)

• occurs in cristae of mitochondria

• produces 32-34 molecules of ATP

Photosynthesis

carbon dioxide + water —> glucose + oxygen + ATP

Cell signalling

• receptors allow signal molecules (ligands) to bind to them

• pathogens can bind to cell receptir

function of endocytosis

cells engulf particles or materials from the outside to the inside of the cell using vesicles

types of endocytosis

• pintcytosis

• phagocytosis

pinocytosis

fluid (containing nutrients) is engulfed by a vesicle from the phospholipid bilayers

phagocytosis

solid particle is englufed through a vesicle

function of exocytosis

exports particles and material out of the cell through vesicles

Stages of meiosis

prophase 1, metaphase 1, anaphase 1, telophase 1, prophase 2, metaphase 2, anaphase 2 and telophase 2

What is meiosis

• contributes to genetic variety

• replication of gametes

• gametes have 23 chromosomes, while body cells have the total 46 chromosomes

• interphase happens before interphase and cytokenisis happens after.

Are the daughter cells of meisosis diploid or haploid?

haploid (n)

prophase 1

• chromosomes condense

• nuclear membrane disintegrates

• spindle fibres form

• chromosomes line up with homologous pairs

  • homologous pairs of same size and same allele location

• homologous pairs transfer genes in crossing over

metaphase 1

• Chromoses line up at the centre of the cell as pairs

anaphase 1

• crossed over chromsomes are pulled away by spindle fibres to opposite poles of the cell

telophase 1

two formed nuclei

prophase 2

• no crossing over

• spindles form

metaphase 2

• chromatids line up at the centre of the cell

• do not pair up, instead line up on top of each other

anaphase 2

sister chromatids are pulled apart from the centromere by the spindle fibres to opposite poles of the cell

telophase 2

nuclei forms in both cells, creating four daughter cells and hence forming 4 cells with 23 chromosomes each.

How many chromsomes does an organism have in a replicated gamete cell with diploid number 28?

14 chromosomes

differences between mitosis and meiosis

mitosis:

• produces 2 genetically identical daughter cells

• genetic variation does not change

• consists of four stages

• daughter cells are diploid

meiosis:

• produes 4 genetically unique daughter cells

• genetic variation increases

• consists of eight stages

• daughter cells are haploid

what is binary fission the replication of?

prokaryotes

binary fission steps

Mitosis steps

What are the types of prokaryotes

archaea and bacteria

characteristics of prokaryotes

• unicellular

• no membrane bound organelles

• no nucleus

• have DNA information in the form of circular chromsomes and plasmids

• cell membrane (cell wall)

• have ribsomes and cytoplasm

types of eukaryotes

eukarya (protsists, animals, plants and fungi)

charactertistics of eukaryotes

• more complex

• multicellular

• have membrane bound organelles (mitochondria, chloroplasts (plants), nucleus, ER and golgi body)

G1

• cell increases in mass

G2

• protein synthesis

• increases in size

S (interphase)

• synthesis of DNA

• Replication of chromosomes

Cytokenisis

cell membrane moves inwards to create daughter cells

How are the chromosomes replicated in binary fission

copying of DNA begins at the sprot of chromosome called origin of replication. This is where the chromosome will replicate the genes and go along the chromosome until all genes have been replicated and there are two genetically identical chromosomes in the prokaryotic cell.

Why is surface area to volume ratio important for cells survival

important to allow cells to quiclly exchange materials and wastes for its survival

Optimum conditions for Bacteria

• 35 - 37 degrees celcius

• neutral pH

• constant supply of water and oxygen

• mechanism removing waste

What types of bacteria benefit humans?

decomposers and nitrogen fixation (←idk what that is either)

decomposers

decomposers break down dead matter into inorganic materials that can be used by producers/plants for growth

Factors affecting growth of microbes

• warmth

• moistre

• ph

• oxygen levels

• nutrients

Nucleolus

site of ribosome synthesis

ribosome

produce proteins

golgi body

recieves proteins from the ER, and packages and distributes them to other parts of the cell

Smooth ER

involved in lipid manufacture and storage

Rough ER

has ribosomes and is involved in production, folding and transportation of proteins

Ribosome

small round bodies that produce proteins

lysosome

small round organelle that contains chemicals that break down particles

vacuole

stores water and nutrients, and supports plant cells

cytoskeleton

supports structure of cell

Limitations of antibiotics

can experience antibiotic resistance

What are the uses of antibiotics

fights bacterial infections

What is the enzyme called in recombinant technology that snips the gene sequence

Resistance enzyme

What is the enzyme called that resticks the gene of interest into the plasmid of a prokaryotic cell

DNA Ligase

How does sugar and salt preserve food

through osmosis

how does cooling food preserve it

slows down enzyme activity that rot food and slows down growth and reproduction of microorganisms.

What is competition

the rivarly between species or in a population for resources

how much energy is passed on at each trophic level

10%

how does fertilisation affect environment

nitrogen in fertilisation seeps in soil and creates an optimum condition for weeds to grow in

what is a niche

describes an organisms physical and environmental conditiosn it requires to survive. it is the role that an organism plays in its community.

what is an ecosystem

a community of organisms and how they interact with their environment.

what is the order of hierarchy

1. domain

2. kingdom

3. phylum

4. class

5. order

6. family

7. genus

8. species