Exam Questions Unit 2- 1 Flashcards
(23 cards)
what is meant by the term chromatid?
one of two DNA molecules that make up a chromosome
what structure is present in animal cells only?
centrioles
what structures are present in animal and plant cells? (9)
- Cytoplasm
- Golgi Apparatus
- endoplasmic reticulum
- cell membrane
- mitochondrion
- lysosome
- nucleus
- nucleolus
- ribosomes
what structures are present in plant cells only? (6)
- cell wall
- chloroplast
- amyloplast
- tonoplast
- plasmodesmata
- permanent vacuole
Name structures found in prokaryotic cells but not in eukaryotic cells (7)
- nucleoid
- pili
- capsule
- peptidoglycan cell wall
- plasmids
- 70s Ribosomes
- mesosome
Explain why the taxonomic groups of living organisms have changed over the years and may continue to change. (3)
- more species have been discovered
- the use or availability of improved microscopes
- in the future technology will continue to develop
What is the number of chromosomes in a primary spermatocyte and in a sperm cell (2)
primary spermatocyte= 46
sperm cell= 23
Explain why several divisions of mitosis are involved in the production of sperm cells (2)
- to increase the number of primary spermatocytes
- large numbers of sperm cells are produced
Explain the meaning of polygenic inheritance
- one characteristic is determined by more than one gene
Explain the meaning of phenotype
the phenotype are the observable characteristics
Explain continuous variation (3)
- when there is a range of characteristics (height, leaves on a tree)
- they are phenotypic feautures that are usually polygenic
- they are also affected by the environment
what is meant by negative correlation?
as one variable increases, the other decreases
Suggest why skin cancer may result from an interaction between genotype and phenotype and the environment (3)
- because skin color is genetic and the exposure to ultraviolet light is environmental
- ultraviolet light is known to cause mutations
- the control of the cell cycle is lost
Explain why starch is a suitable storage molecule (3)
- starch contains large numbers of glucose molecules
- it is branched so that it can release energy easily
- compact so that more glucose can fit into a particular space
Suggest why the cells in the parenchyma tissue depend on the functions of xylem vessels (5)
- supplies water to keep cells turgid
- supplies magnesium for synthesis of chlorophyll
- supplies nitrate for synthesis of DNA
- supplies calcium for cell wall structure
- supports the leaves so they are exposed to sunlight
explain what is meant by biodiversity (2)
- the variety of alleles
- the number of different species in a habitat
Describe how plants from the rainforest could be tested for their antimicrobial properties (7)
- test different parts of each plant
- grind up the plant material
- add bacteria to agar
- soak discs in extract
- incubate bacteria at temp in the rage from 20-35~ for 1 to 7 days
- use aseptic techniques (sterile equipment)
- repeat and calculate mean
Describe what the next steps would be in the development of new medicines, if some plants from rainforest were found to have antimicrobial properties. (6)
- testing which bacteria were affected
- determine concentration to use
- animal testing
- testing on small groups of healthy people
- testing on small groups of patients
- testing on large groups of patients
Describe methods that could be used to conserve endangered plant species (2)
- store seeds in seed banks
- take cuttings and grow them in greenhouses
Compare stem cells that are totipotent with stem cells that are pluripotent (2)
- both are unspecialiszed
- totipotent can become all cell types while pluripotent can become most cell types
Describe how the four different cell types (nerve, muscle, pancreatic and heart muscle cells) are formed from stem cells. (7)
- mitosis to increase number of cells
- responding to environmental/chemical stimulus
- differential gene expression
- for example gene for production of insulin is switched on in the pancreatic cells
- transcription occurs at active genes
- proteins are produced from this mRNA
- this protein permanently modifies cell
Explain why it is possible that two species of birds are found in the same habitat (4)
- the birds occupy different niches
- they have different beak length
- have different sources of food
- to avoid competition with eachother
How a cell gains function, how a cell changes structure, how a cell differentiates? (5)
- there is a chemical stimulus which causes DNA methylation/gene expression change
- genes are activated (switched on) or off
- activated genes will produce mRNA
- mRNA translated into protein
- protein permanently modifies the cell
