Karteikarten
B5 - growth and development
Karten in diesem Stapel (37)
- 1-Define a specialised cell ... -Give and example and some of its functions ....Specialised cell= a specialised cell has a structure that allows it to carry out a particular function
RED BLOOD CELLS=
-contains protein haemoglobin for transport of 0xygen
-no nucleus
-Biconcave shape
- can squeeze down narrow capillaries in single file - 2What is a tissue cell and a exampleTissue=a group of cells of similar structure that perform a stared function - ANIMAL TISSUES = muscle tissues and nervous tissues
- 3What is a organ and give an exampleAn organ is a structure of made of a group of different tissues working together to perform specific functions
PLANT ORGANS= stem&leaves - 4What is an organ system and a exampleAn organ system is a group of organs that co-ordinate to perform related functions
- 5How do multi cellular organisms originate? (NAME THE STEPS)STEPS=
-sexual intercourse
-fertilisation- fusion of the nuclei sperm and egg cell
-a fertilised egg cell is called a zygote
-the zygote divides by mitosis to form an embryo
-Fetus (8weeks after fertilisation to birth) - 6What's a stem cell?unspecialised cell has the potential to develop into different types of specialised cells
- 7Give the 8 cell stage development-After this stage most cells become specialised to a particular function& begin to form different types of tissues
-some cells remain partially specialised with the potential to still develop into many different types of cells - called adult stem cells
-specialised cells no longer hold the potential to change into different types of cell & so adult cells are of interest in medicine - 8Describe Animal growth ...Animal Growth
-growth occurs throughout the body but EVENTUALLY STOPS
-after this time, some cells (stem cells) continue to divide and then enlarge e.g. skin cells
-at the same time, other cells in the body are also dying at the same rate. Resulting in NO overall growth - 9Describe plant growth ...PLANT GROWTH
-they get larger overall but they only grow at specific places called Meristem regions, they're mitotically active- actively dividing
-Meristem cells are unspecialised cells that are found at shoot tips, root tips, in buds and in the stem
SAM= shoot apical meristem
RAM= root apical meristem - 10How are adult stem cells and meristematic regions different? (How can meristems cells be used to clone plants?)Meristematic cells are completely unspecialised meaning they have higher potential where as adult stem cells are partially programmed meaning they have less potential
-cutting of plants used to clone take part of plant with unspecialised meristertatic cells - can make new cells which means whole new plant can be made from a cutting - 11What are clones? Name the adv/dis of cloning plants ... What's a mono-culture?clones= genetically identical organisms
Cloning plants= -saves money
-select characteristics
-quick and easy
DISADVANTAGES -No variety so if disease will kill all plants
Mono-culture= 1 identical crop with copied DNA so they're all identical &carry the same genes - 12Define Tropism Stimulus PhototropismTROPISM- a growth in response to a stimulus, plants grow towards sources of water and light-which they need to survive and grow
STIMULUS- a change in environment
PHOTOTROPISM- plants grow in the direction of light - 13Explain positive phototropismPositive=
-Stem tip
-Grows towards light
-to get maximum light for photosynthesis - 14Explain negative phototropismNEGATIVE=
-root tip
-growth away from light
-less chance of drying out - 15Describe positive geotropism ...Positive geotropism=
-root tip
-towards gravity
-less chance of finding light higher chance of finding light higher chance of finding water - 16Describe negative geotropism ...Negative geotropism=
-stem tip
-growth away from gravity
-more chance of finding light - 17Define fully and explain phototropism -multilateral light -unlateral light-in multilateral light the plant shoot grows straight up& the leaves form a mosaic around the stem so that each leaf obtains the maximum amount of light
-unlateral light the plant bends towards the light so that leaves obtain maximum of light - bending in response to the light is called PHOTOTROPISM - 18What are Auxins ? define and explain (where are they found/ what do they do to the plant?)Auxins= chemicals that control growth near the tips of shoots and roots
Auxins produced in the tips and diffuses backwards to stimulate cell elongation process
If the tip of a shoot is removed no auxins are available the shoot may stop growing
Auxins is a response of plants to light, gravity and water - 19Describe DNA's structure ...DNA molecule has 2 strands that coil together in shape of a double helix
-Each strand made up of nucleotides
-Each nucleotide contains a small molecule called a base- 4 different bases
-2 strands held together by the bases- always pairs up the same way - 20Draw and label DNA Structure
- 21Name the 4 different bases and what bases only join together ...Adenine and Thymine (A&T)- only join together
Cytosine and Guanine (C&G)- only join together - 22Describe 3 stages of DNA replication ...-2 strands of the DNA molecule separate - hydrogen bonds are broken by DNA helicase (enzyme)
-the 2 strands can now act as templated. - 23What are chromosmes ?-chromosomes carry genetic information (DNA)
-DNA contains genes that code for proteins in our bodies
-each human cell has 46 single chromosomes - 24What's the difference between mitosis and meiosis?MITOSIS- type of cell division that is involved in growth, tissue repair and cell replacement
MEIOSIS- type of cell division that produces gametes (sex cells) needed during sexual reproduction - 25Describe the cell cycle ...cell cylce results in cell division & the rpoduction of 2 genetically identical daugheter cells from the original parent cell.
- 26Descrie the process of Mitosis ...1.chromosomes condense and become visable at the start of mitosis
2.nuclear membrane breaks down
3.spindle fibres form &attach to chromosomes
4. spindle fibres line chromosomes along the centre of the cell
5. spindle fibres pull the chromosomes apart to opposite polls of the cell
6.spindle fibres disintergrate & the nuclear membrane reforms
7.chromosomes unwind, no longer visable, cytoplasm divides again giving 2 genetically identicall cells - 27What's a -Diploid -Haploid -ZygoteDiploid- cell containing 23 pairsof chromosomes (46 single)- normal body cells
Haplod- cell containing 23 single chromosomes (half genetic info needed)
Zygote- cell made when a sperm cell fertilises an egg cell in sexual reproduction - 28Describe Meiosis ...FIRST DIVISION- the chromosme pairs line up in the centre of cell - pulled apart so the new cell has 1 copy of each chromosomes
some of the dads &some of the mums goes in cell
SECOND DIVISION- in this division the chromosomes line up again in centre of the cell
Geet 4 gametes each with only a SINGLE SET of chromosomes in it - 29Describe Gametes ...these have 23 single chromosomes
During sexual reproduction - egg and sperm cell combine to make zygote - once combined the zygote has 46 chromosomes - 30Name the 4 catergories assosiated with functions of proteins and examples - there useStructual- build cells and tissues e.g. collagen makes artery walls srtonger
Hormones- chemical messanger e.g. insuline controls glucose levels
Carrier molcules- e.g. haemoglobin carries oxygen in the blood
Enzymes- speed up chemical reactions - 31Describe the use of MRNA and Ribosomes to create proteins ... (why DNA can't leave the nucleus)1. 2 DNA strands unzip- molecule of MRNA made using 1 strand of DNA asa template
2. messanger RNA molecule moves out of the nucleus and joins witha ribosome in the cytoplasm
3. Job of the ribosome is to stick amino acids togetehr in a chain to make a protein - following the order of bases in the MRNA
why? - cant leaves as DNA is to big & need to protect DNA from cytoplasm reactions - 32Define triplet code and the DNA bases and MRNA basesTriplet code= three bases code for 1 amino acid (reads 3 letter e.g. AUU)
MRNA = AUGG
DNA= ATCG - 33Describe how genes can be switched on/off causing cell specialisation ...An embryonic stem cell has total potential meaning it can make any protein where as the cells that are specialised certain genes are switched off meaning the protein isn't made
-as this gene is switching it enables different types of specialised cells to bbe present. - 34Define a stem cell and where they're found ...Stem cell= unspecialised cell that can go on to become any type of specialised cell
FOUND= embryonic -total potetial beofre it is a fetus
Adult stem cell- limited potential - fetus/baby/adult/bone marrow/brain/eye - 35Why are stem cells useful?Embryonic= cells extracted used to transform specialised cells to replace faulty cell in sick person- heart muscle cell =heart disease
Adult+ already used to cure disease- blood disease - anaemia treated using bone marrow transplants - contains same stem cells that can replace faulty old ones - 36Arguments FOR using embryonic stem cells ...-potential to cure currently incurrable diseases~parkinsons/cancer
-greater saving lives
-ball of cells~not a human or fetus yet
-found the technolgoy~should use it
-embryo's taken from fertility clinic would've been thrown away - 37Arguments AGAINST using embryonic stem cells ...-'murder' if using these cells
- 'playing god'
~goes agaianst gods plans
~don't play with nature
-human rights of embryo
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- Science Karteikarten am B5 - growth and development, erstellt von Cerys High-Milam am 13/11/2016.
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- Cerys High-Milam
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