biology - 5th year

what are the 2 basic groups of autotrophs

photosynthetic and chemosynthetic

How do photosynthetic organisms make their food

organisms make their own food using light energy carbon dioxide and water (mostly plants)

how do chemosynthetic organisms make own their food

make their their food from chemicals other than carbon dioxide and water e.g nitrogen-fixing bacteria that live in the root nodules of leguminous plants(pea and bean)

what is food

is a source of materials required by an organism to provide the energy to stay alive , grow and reproduce

what are autotrophs and how do they make their food

are organisms that make their own food from simple inorganic materials in their own environment

what are the 5 major heterotroph groups

herbivores, omnivores, carnivores, detritus feeders, decomposers

what are herbivores

are

what are heterotrophs

what does cell continuity mean

cell continuity means that the division of pre- existing living cells has produced all cells living today

what are chromosomes

chromosomes are thread- like structures made up of DNA and protein that contain genetic information

what is a karyotype

the karyotype is the complete set of chromosome of an individual and what it looks like under a light microscope

what are homologous chromosomes

pairs of chromosomes with the same size and shape and contain genes for the same characteristics

what is a genome

the sequence of all the bases that make up all the chromosomes in an organism

what is the diploid number of humans

46

what is the haploid number of organisms

23

what does diploid mean

when there are two sets of chromosomes one from the mother and one from the father (shortened to 2n)

what does haploid mean

when an organism has one set of chromosomes

what cells in the human body are not diploid

gametes (sperm and egg cells)

what are examples of haploid organisms

yeast and fungi cells

what are triploid organisms

organisms with three sets of chromosomes

what are tetraploid organisms

organisms with four sets of chromosomes e.g salmon

what happens in part1 of the interphase

the cell grows to its normal size makes proteins and carries out its daily functions while that is happening the cell organelles such as the mitochondria and chloroplasts replicate

what happens in part 2 of interphase

the DNA replicates

what happens in part 3 of interphase

the cell makes final preparation for division (mitosis)

what is mitosis

the process in which the nucleus divides to form two cells genetically identical to its parent cell

what kind of cells use mitosis

prokaryotic cells (cells with membrane bound organelles such as mitochondria and chloroplasts)

what is the equivalent process in other types of cells

eukaryotic cells use binary fission

what is the function of mitosis in unicellular organisms

in unicellular organisms such as amoeba the main function is reproduction

what is function of mitosis in multicellular organisms

growth and repair of cells

what are the four main stages of mitosis

prophase, metaphase, anaphase, telophase

what happens in the prophase

• chromatin condenses and becomes visible as rod shaped structures

• nuclear membranes break down

• the centrioles move toward opposite poles

• spindle fibres start to form

what happens in the metaphase

• the chromosomes line up on the equator

• the spindle fibres attach to the centromeres

• and the nuclear membranes have completely disappeared

what happens in the anaphase

• the spindle fibres contract

• chromosomes are pulled apart

• one copy of each chromosome is pulled towards each pole

what happens in the telophase

• the nuclear membranes reappear

• the chromosomes begin to unwind

• and cell division begins

what happens in cytokinesis (not officially part of mitosis)

• cell division is complete

• in plant cells the cell plate begins to form

• in animal cells the cleavage furrow appears

what is meiosis

meiosis is the division of a diploid nucleus producing 4 haploid genetically different nuclei

what are the functions of meiosis

1. gamete formation (production of sperm and egg cells in human)

2. pollen grain formation (spore formation in flowering plants)

what is the end result of mitosis

• two cells that are genetically identical with the same number of chromosomes

end result of meiosis

four cells which are all genetically different and half the number of chromosomes as the parent cell

what is cancer

when the cells lose their normal control of mitosis leading to the formation of a tumour

causes of cancer

• ionising radiation e.g x-rays

• ultraviolet radiation e,g sunbeds

• excessive drinking of alcohol (spirits)

types treatments for cancer

1. surgery (removal of tumour)

2. chemotherapy: when chemicals are administered to attack and kill cells that are actively dividing

3. radiotherapy: using high energy radiation e.g gamma rays to shrink the tumour

what is metabolism

the sum of all chemical reactions that occur in an organism

what are the five characteristics of life

1. organisation

2. reproduction

3. nutrition

4. excretion

5. response

what is nutrition

the process by which living organisms obtain their food

what is excretion

the removal of waste products of metabolism

what is response

organisms react to both internal and external changes e.g plants stomata only open in light

what is reproduction

the ability for organisms to produce offspring