science transition test revision (biology) Flashcards
define nucleus
DNA, Inheritance and Variation
the nucleus controls what happens in the cell
define DNA
DNA, Inheritance and Variation
deoxyribonucleic acid.
the material inside the nucleus of cells, carrying the genetic information
define double helix
DNA, Inheritance and Variation
the shape of DNA molecules with two strands twisted in a spiral
define base pair
DNA, Inheritance and Variation
the pair of bases that connect the strands of DNA
define bond
DNA, Inheritance and Variation
the chemical link that holds molecules together
define gene
DNA, Inheritance and Variation
the basic unit of genetic material inherited from our parents
define heredity
DNA, Inheritance and Variation
genetic information that determines an organism’s characteristics, passed down from one generation to another
define variation
DNA, Inheritance and Variation
differences between individuals
define continuous variation
DNA, Inheritance and Variation
variation that can be in a range
e.g. hand span, arm span
define discontinuous variation
DNA, Inheritance and Variation
differences between individuals in a characteristic that can only be put into different categories
e.g. eye colour, blood type
define environmental variation
DNA, Inheritance and Variation
differences between individuals of a species due to factors in their surroundings
give four examples of inherited variation
DNA, Inheritance and Variation
- rolling tongue
- hair colour
- height
- eye colour
give four examples of environmental variation
DNA, Inheritance and Variation
- tattoos
- language
- religion
- weight
give three examples of continuous variation
DNA, Inheritance and Variation
- height
- weight
- arm span
give three examples of discontinuous variation
DNA, Inheritance and Variation
- eye colour
- hair colour
- blood group
define sperm cell
Reproduction
the male sex cell (gamete)
define egg cell
Reproduction
the female sex cell (gamete)
define ovary
Reproduction
the female reproductive organ that releases egg cells
define fertilisation
Reproduction
the fusing of the male and female sex cells
define placenta
Reproduction
the organ that allows substances to pass between the mother’s blood and the baby’s blood
define testes
Reproduction
the male reproductive organ that releases sperm cells
define gestation
Reproduction
the period between fertilisation and birth, also known as pregnancy
define embryo
Reproduction
tiny new human life which grows by cell division from a fertilised egg cell
define fetus
Reproduction
the unborn baby after around 8 weeks of pregnancy
define amniotic fluid
Reproduction
a fluid which surrounds the fetus and helps protect it
define sexual reproduction
Reproduction
producing new organisms by the joining of two sex cells
define menstruation
Reproduction
when the lining of the uterus breaks down every month if the egg isn’t fertilised. also known as a period
define asexual reproduction
Reproduction
producing new organisms from only one parent
define cell
Cells
basic unit of life
unicellular - only one cell
multicellular - many cells
define cell membrane
Cells
controls the movement of substances in and out of the cell
define cytoplasm
Cells
jelly-like substance where chemical reactions take place
define nucleus
Cells
it carries genetic information and controls the cell
define mitochrondia
Cells
where respirations take place
define cell wall
Cells
made of cellulose, provides support to the cell
define vacuole
Cells
it contains cell sap
define chloroplasts
Cells
it contains the green pigment chlorophyll, the site of photosynthesis
define organ
Cells
something made from different groups of specialised cells all working together
define tissue
Cells
something made from just one type of specialised cell
define organ system
Cells
when a number of organs work together
define synovial joint
Cells
a freely moveable joint
define photosynthesis
Photosynthesis
process carried out where plants make their own food
carbon dioxide + water –≥ glucose + oxygen
define chlorophyll
Photosynthesis
green pigment in chloroplasts of plant cells - it enables photosynthesis to take place
define chloroplasts
Photosynthesis
contains the green pigment chlorophyll - is the site of photosynthesis
define waxy cuticle
Photosynthesis
waxy layer, prevents water loss
define upper epidemis
Photosynthesis
is thin and transparent to allow light to pass through
define palisade mesophyll
Photosynthesis
main region of photosynthesis; lots of palisade cells containing chloroplasts
define spongy mesophyll
Photosynthesis
cells are loosely packed; contains air spaces between cells allowing gas exchange
define stomata
Photosynthesis
each stomata is surrounded by guard cells, which control whether they’re open or closed
define lower epidemis
Photosynthesis
contains stomata to regulate the loss of water vapour
define petals
Photosynthesis
they’re brightly coloured to attract insects
define stamen
Photosynthesis
the male part of a flower
define stigma
Photosynthesis
the top of the female part of a flower which attracts pollen
define anthers
Photosynthesis
produces male sex cells
define ovary
Photosynthesis
produces female sex cells
define nectary
Photosynthesis
produces a sugary solution called nectar, which attracts insects
