Chromosomes and DNA calculations

{"questions":[{"content":"How many chromosomes does cherry sperm contain if the leaf cell contains $16$ chromosomes?[[fill_choice_big-1]]","widgets":{"fill_choice_big-1":{"type":"fill_choice_big","options":["$8$","$16$","$32$"],"placeholder":0,"answer":0}},"step":1,"hints":["A leaf cell is a somatic cell, which means it is diploid: $2n=16$.","Sperm is a gamete, which means it is haploid, that is, it contains:<br />$$n = \\frac{2n}{2} = \\frac{16}{2} = 8$$"]},{"content":"How many chromosomes does a wheat root cell contain if the sperm nucleus contains $14$ chromosomes?[[fill_choice_big-17]]","widgets":{"fill_choice_big-17":{"type":"fill_choice_big","options":["$28$","$14$","$7$"],"placeholder":0,"answer":0}},"step":1,"hints":["The sperm nucleus is a gamete, which means it contains a haploid set of chromosomes: $n=14$.","The wheat root cell is a somatic cell, that is, diploid, and contains:<br />$$2n = 2 \\times n = 2 \\times 14 = 28$$"]},{"content":"An apricot gamete contains $8$ chromosomes. How many chromosomes does an apricot root cell have? [[fill_choice_big-31]]","widgets":{"fill_choice_big-31":{"type":"fill_choice_big","options":["$8$","$4$","$16$"],"placeholder":0,"answer":2}},"step":1,"hints":["The apricot gamete is a haploid cell, that is: $n=8$.","The root cell is somatic, that is, diploid:<br />$$2n = 2 \\times 8 = 16$$"]},{"content":"On the outgrowth of the male shield fern, as a result of mitosis, a sperm with $82$ chromosomes was formed. Determine the number of chromosomes in the cell of the germ.[[fill_choice_big-63]]","widgets":{"fill_choice_big-63":{"type":"fill_choice_big","options":["$82$","$42$","$21$"],"placeholder":0,"answer":0}},"explanation":"If a fern sperm is formed as a result of mitosis, this means that it has the same set of chromosomes as the cell from which it originated.<br /><br />In ferns, the prothallus is a gametophyte, it is haploid, and its cells divide by mitosis to form gametes. Therefore, sperm and germ cells have the same number of chromosomes.<br /><br />Consequently, the number of chromosomes in the germ cell is the same as in the sperm - $82$."},{"content":"How many chromosomes does the sperm of a flowering plant contain if the nucleus of a leaf cell contains $32$ chromosomes?[[fill_choice_big-101]]","widgets":{"fill_choice_big-101":{"type":"fill_choice_big","options":["$16$","$32$","$64$"],"placeholder":0,"answer":0}},"step":1,"hints":["The leaf cell of a flowering plant is a somatic cell, it is diploid: $2n=32$.","Sperm is a gamete, it is haploid, which means it contains:<br />$$n = \\frac{32}{2} = 16$$"]},{"content":"The triploid endosperm cell of rye contains the $21$ chromosome. How many chromosomes does a cell of its leaf contain?[[fill_choice_big-153]]","widgets":{"fill_choice_big-153":{"type":"fill_choice_big","options":["$14$","$21$","$7$"],"placeholder":0,"answer":0}},"step":1,"hints":["The endosperm cell of rye is triploid ($3n$) and contains the $21$ chromosome. In flowering plants, the endosperm is triploid, formed after the fusion of one sperm with two nuclei of the central cell. Therefore, $3n$, while leaf cells are ordinary somatic, with a diploid set.","Find the haploid set:<br />$$n = \\frac{21}{3} = 7$$","The leaf cell is somatic, it is diploid ($2n$):<br />$$2n = 2 \\times 7 = 14$$"]},{"content":"How many DNA molecules are contained in the cell nucleus before the onset of mitosis, if the original cell contains $104$ chromosomes?[[fill_choice_big-198]]","widgets":{"fill_choice_big-198":{"type":"fill_choice_big","options":["$208$","$104$","$52$"],"placeholder":0,"answer":0}},"step":1,"hints":["Before the start of mitosis, each chromosome doubles (DNA replication), but the number of chromosomes remains the same, each simply consists of two sister chromatids, i.e. two DNA molecules.","If the cell has $104$ chromosomes, then before mitosis there will be:<br />$$\\text{Number molecules DNA} = 104 \\times 2 = 208$$"]},{"content":"The number of autosomes in a rabbit egg is $21$. How many sex chromosomes does a rabbit egg contain?[[fill_choice_big-263]]","widgets":{"fill_choice_big-263":{"type":"fill_choice_big","options":["$22$","$21$","$1$"],"placeholder":0,"answer":2}},"step":1,"hints":["An egg is a gamete, which means it contains a single (haploid) set of chromosomes. By convention, the $21$ chromosome is an autosome, and another chromosome is a sex chromosome.","This means that the sex chromosomes in the egg are:<br />$$1$$<br />The total number of chromosomes in an egg is $21+1=22$, but the question asks specifically about sex chromosomes."]},{"content":"How many sex chromosomes does a human sperm contain if the haploid set contains $23$ chromosomes?[[fill_choice_big-340]]","widgets":{"fill_choice_big-340":{"type":"fill_choice_big","options":["$1$","$23$","$22$"],"placeholder":0,"answer":0}},"hints":["Haploid set in sperm: $n = 23$. The sperm contains one sex chromosome, which determines the sex of the future organism upon fertilization.","Of these, one chromosome is a sex chromosome (either X or Y), the rest $22$ are autosomes."]},{"content":"How many chromosomes does the nucleus of a diploid cell contain if the gamete of an organism of this species contains a $21$ chromosome?[[fill_choice_big-458]]","widgets":{"fill_choice_big-458":{"type":"fill_choice_big","options":["$42$","$21$","$14$"],"placeholder":0,"answer":0}},"step":1,"hints":["Gamete is a haploid cell, which means: $n = 21$.","A diploid cell contains double the number of chromosomes:<br />$$2n = 2 \\times 21 = 42$$"]},{"content":"From the generative cell of a red currant pollen grain, as a result of mitosis, a sperm containing $8$ chromosomes was formed. Determine the number of chromosomes in the generative cell of a pollen grain.[[fill_choice_big-673]]","widgets":{"fill_choice_big-673":{"type":"fill_choice_big","options":["$8$","$16$","$4$"],"placeholder":0,"answer":0}},"explanation":"If a sperm was formed as a result of mitosis of a generative cell, then the number of chromosomes in it and in the generative cell is the same. By condition, the sperm contains $8$ chromosomes.<br /><br />This means that the generative cell also contains the same amount."},{"content":"The number of chromosomes of a crayfish zygote is $116$. How many chromosomes does a crayfish green gland cell contain?[[fill_choice_big-780]]","widgets":{"fill_choice_big-780":{"type":"fill_choice_big","options":["$116$","$232$","$58$"],"placeholder":0,"answer":0}},"explanation":"A zygote is a fertilized egg, that is, the first somatic (diploid) cell of the body. All somatic cells of the body have the same number of chromosomes, equal to the number of chromosomes in the zygote.<br /><br />The green gland cell of a crayfish is also a somatic cell, which means it contains the same diploid set as the zygote."},{"content":"How many DNA molecules does each chromosome contain before mitosis?[[fill_choice_big-873]]","widgets":{"fill_choice_big-873":{"type":"fill_choice_big","options":["$2$","$1$","$3$"],"placeholder":0,"answer":0}},"explanation":"Before mitosis, each chromosome consists of two sister chromatids, and each chromatid contains one DNA molecule. After DNA replication in interphase, each chromosome doubles and contains $2$ DNA molecules connected at the centromere."},{"content":"On the haploid plant of horsetail, as a result of mitosis, an egg cell with $108$ chromosomes was formed. Determine the number of chromosomes in the cell of the germ.[[fill_choice_big-1000]]","widgets":{"fill_choice_big-1000":{"type":"fill_choice_big","options":["$108$","$54$","$216$"],"placeholder":0,"answer":0}},"explanation":"If the egg was formed as a result of mitosis on a haploid germ, then the number of chromosomes in the germ and in the egg will be the same (mitosis does not change the number of chromosomes).<br /><br />In horsetail, the prothallus is a haploid gametophyte. Its cells divide by mitosis to form gametes, so the number of chromosomes in the germ cell and in the egg cell is the same.<br /><br />According to the condition, in the egg cell: $n=108$, and therefore in the cell of the germ."},{"content":"How many chromosomes are there in a cell in the prophase of the first division of meiosis, if the diploid set contains $80$ chromosomes? [[fill_choice_big-1164]]","widgets":{"fill_choice_big-1164":{"type":"fill_choice_big","options":["$80$","$160$","$40$"],"placeholder":0,"answer":0}},"explanation":"In prophase I of meiosis, the cell is still diploid, and the number of chromosomes does not change - just each chromosome already consists of two sister chromatids.<br /><br />If the diploid set is: $2n=80$, then in prophase I of meiosis the cell contains $80$ chromosomes."},{"content":"How many DNA molecules will each chromosome contain at the end of interphase?[[fill_choice_big-1311]]","widgets":{"fill_choice_big-1311":{"type":"fill_choice_big","options":["$2$","$1$","$3$"],"placeholder":0,"answer":0}},"explanation":"At the end of the interphase (namely after the S stage - synthetic phase), each chromosome has already doubled and consists of two sister chromatids.<br /><br />Each chromatid contains one DNA molecule, therefore, after DNA replication in interphase, each chromosome consists of 2 DNA molecules."},{"content":"How many DNA molecules are contained in the cell nucleus at the end of the telophase of the second division of meiosis, if the diploid set contains $44$ chromosomes?[[fill_choice_big-1451]]","widgets":{"fill_choice_big-1451":{"type":"fill_choice_big","options":["$22$","$44$","$88$"],"placeholder":0,"answer":0}},"step":1,"hints":["Let's look at the stages: diploid set $2n = 44 \\Rightarrow n = 22$.","At the end of the second meiotic division, haploid cells are formed (each with $22$ chromosomes). After telophase II, each chromosome consists of one chromatid, that is, one DNA molecule.","This means that in the nucleus of each cell:<br />$$\\text{Number molecules DNA} = 22$$"]},{"content":"How many nucleotides in a gene section encode a protein fragment of $35$ amino acid residues?[[fill_choice_big-1]]","widgets":{"fill_choice_big-1":{"type":"fill_choice_big","options":["$105$","$35$","$70$"],"placeholder":0,"answer":0}},"step":1,"hints":["The genetic code is triplet: $1$ amino acid = $3$ nucleotide. The stop codon does not encode an amino acid, but the problem says “they encode a protein fragment from $35$ amino acids,” so we take into account only those that encode.","Each amino acid is encoded by three nucleotides (one triplet, or codon):<br />$$35\\ \\text{amino acids} \\times 3 = 105\\ \\text{nucleotides}$$"]},{"content":"How many amino acids does $900$ code for nucleotides?[[fill_choice_big-6]]","widgets":{"fill_choice_big-6":{"type":"fill_choice_big","options":["$300$","$600$","$900$"],"placeholder":0,"answer":0}},"step":1,"hints":["The genetic code is triplet - $1$ amino acid = $3$ nucleotide.","Each amino acid is encoded by $3$ nucleotides ($1$ codon):<br />$$\\frac{900}{3} = 300$$"]},{"content":"In a DNA molecule, the number of nucleotides with guanine is $20\\%$ of the total. How many nucleotides are there in $\\%$ with thymine in this molecule?[[fill_choice_big-31]]","widgets":{"fill_choice_big-31":{"type":"fill_choice_big","options":["$80$","$30$","$60$"],"placeholder":0,"answer":1}},"step":1,"hints":["The rules of complementarity apply in the DNA molecule: guanine ($G$) = cytosine ($C$) and adenine ($A$) = thymine ($T$). If guanine is $20\\%$, then cytosine is also $20\\%$:<br />$$G + C = 20\\% + 20\\% = 40\\%$$","Remaining: $100\\% — 40\\% = 60\\%$. Divide the remainder equally between adenine and thymine:<br />$$T = \\frac{60\\%}{2} = 30\\%$$"]},{"content":"What percentage of nucleotides with cytosine does DNA contain if the proportion of its adenine nucleotides is $10\\%$ of the total?[[fill_choice_big-53]]","widgets":{"fill_choice_big-53":{"type":"fill_choice_big","options":["$40$","$60$","$90$"],"placeholder":0,"answer":0}},"step":1,"hints":["The rules of complementarity apply in the DNA molecule: adenine ($A$) = thymine ($T$) and guanine ($G$) = cytosine ($C$). If adenine is $10\\%$, then thymine is also $10\\%$:<br />$$A + T = 10\\% + 10\\% = 20\\%$$","We will divide the remaining $100\\% — 20\\% = 80\\%$ equally between guanine and cytosine:<br />$$C = \\frac{80\\%}{2} = 40\\%$$"]},{"content":"How many nucleotides in the gene encode the sequence $100$ of amino acids in a protein molecule? [[fill_choice_big-95]]","widgets":{"fill_choice_big-95":{"type":"fill_choice_big","options":["$300$","$200$","$100$"],"placeholder":0,"answer":0}},"step":1,"hints":["Genetic code is triplet: $1$ amino acid = $3$ nucleotide. The stop codon does not encode an amino acid, but the problem says “they encode a protein fragment of $100$ amino acids,” so we take into account only those that encode.","Each amino acid is encoded by three nucleotides (one triplet, or codon):<br />$$100\\ \\text{amino acids} \\times 3 = 300\\ \\text{nucleotides}$$"]},{"content":"In a DNA molecule, the number of nucleotides with guanine is $10\\%$ of the total. How many nucleotides are there in $\\%$ with adenine in this molecule?[[fill_choice_big-144]]","widgets":{"fill_choice_big-144":{"type":"fill_choice_big","options":["$40$","$20$","$90$"],"placeholder":0,"answer":0}},"step":1,"hints":["The rules of complementarity apply in the DNA molecule: adenine ($A$) = thymine ($T$), guanine ($G$) = cytosine ($C$). If guanine is $10\\%$, then cytosine is also $10\\%$:<br />$$G + C = 10\\% + 10\\% = 20\\%$$","We will divide the remaining $100\\% — 20\\% = 80\\%$ equally between adenine and thymine:<br />$$A = \\frac{80\\%}{2} = 40\\%$$"]},{"content":"In a DNA molecule, the number of nucleotides with cytosine is $30\\%$ of the total. What is the percentage of nucleotides with adenine in this molecule?[[fill_choice_big-210]]","widgets":{"fill_choice_big-210":{"type":"fill_choice_big","options":["$20$","$70$","$40$"],"placeholder":0,"answer":0}},"step":1,"hints":["The rules of complementarity apply in the DNA molecule: adenine ($A$) = thymine ($T$), guanine ($G$) = cytosine ($C$). If cytosine is $30\\%$, then guanine is also $30\\%$:<br />$$G + C = 30\\% + 30\\% = 60\\%$$","We will divide the remaining $100\\% — 60\\% = 40\\%$ equally between adenine and thymine:<br />$$A = \\frac{40\\%}{2} = 20\\%$$"]},{"content":"Protein consists of $60$ amino acids. Determine the number of nucleotides in a DNA molecule encoding this protein.[[fill_choice_big-281]]","widgets":{"fill_choice_big-281":{"type":"fill_choice_big","options":["$180$","$60$","$120$"],"placeholder":0,"answer":0}},"step":1,"hints":["Genetic code is triplet: $1$ amino acid = $3$ nucleotide. The stop codon does not encode an amino acid, but the problem says “they encode a protein fragment of $60$ amino acids,” so we take into account only those that encode.","Each amino acid is encoded by three nucleotides (one triplet, or codon):<br /><br />$$60\\ \\text{amino acids} \\times 3 = 180\\ \\text{nucleotides}$$"]},{"content":"What number of nucleotides in the gene encodes the primary structure of a protein consisting of $300$ amino acids?[[fill_choice_big-363]]","widgets":{"fill_choice_big-363":{"type":"fill_choice_big","options":["$900$","$300$","$1200$"],"placeholder":0,"answer":0}},"step":1,"hints":["Genetic code is triplet: $1$ amino acid = $3$ nucleotide. The stop codon does not encode an amino acid, but the problem says “encodes the primary structure of the protein from $300$ amino acids,” so we take into account only those that encode.","Each amino acid is encoded by three nucleotides (one triplet, or codon):<br /><br />$$300\\ \\text{amino acids} \\times 3 = 900\\ \\text{nucleotides}$$"]},{"content":"The primary annual production of the ecosystem is $630{,}000$$kJ$. Indicate the amount of energy supplied to the second trophic level (in kilojoules).[[fill_choice_big-1]]","widgets":{"fill_choice_big-1":{"type":"fill_choice_big","options":["$63{,}000$","$630{,}000$","$6{,}300$"],"placeholder":0,"answer":0}},"step":1,"hints":["The rule according to which the transfer of energy between trophic levels occurs with a loss of about $90\\%$, and only ~$10\\%$ is transferred further, was formulated by the American ecologist Raymond Linderman in 1942.","Let's apply Linderman's rule to the problem:<br /><br />Primary production (1-th trophic level) = $630{,}000 \\, \\text{kJ}$.","Energy supplied to the second trophic level (herbivores) according to the rule $10\\%$: $630{,}000 \\times 0{,}1 = 63{,}000\\,\\text{kJ}$."]},{"content":"The primary annual production of the ecosystem is $540{,}000$$kJ$. Indicate the amount of energy supplied to the fourth trophic level (in kilojoules).[[fill_choice_big-13]]","widgets":{"fill_choice_big-13":{"type":"fill_choice_big","options":["$540$","$54{,}000$","$5{,}400$"],"placeholder":0,"answer":0}},"step":1,"hints":["The rule according to which the transfer of energy between trophic levels occurs with a loss of about $90\\%$, and only ~$10\\%$ is transferred further, was formulated by the American ecologist Raymond Linderman in 1942.","Let's apply Linderman's rule to the problem:<br /><br />Primary production (1-th trophic level) = $540{,}000 \\, \\text{kJ}$<br />Energy supplied to the second trophic level (herbivores) according to the rule $10\\%$: $540{,}000 \\times 0{,}1 = 54{,}000\\,\\text{kJ}$.","3 level (primary predators): $54{,}000 \\times 0{,}1 = 5{,}400\\,\\text{kJ}$.","4 level (secondary predators): $5{,}400 \\times 0{,}1 = 540\\,\\text{kJ}$."]},{"content":"The energy supplied to the third trophic level is $7{,}300$$kJ$. Indicate the value of the primary annual production of the ecosystem (in kilojoules).[[fill_choice_big-34]]","widgets":{"fill_choice_big-34":{"type":"fill_choice_big","options":["$730{,}000$","$730$","$73{,}000$"],"placeholder":0,"answer":0}},"step":1,"hints":["The rule according to which the transfer of energy between trophic levels occurs with a loss of about $90\\%$, and only ~$10\\%$ is transferred further, was formulated by the American ecologist Raymond Linderman in 1942.","Let's apply Linderman's rule to the problem:<br /><br />Energy supplied to the third trophic level (primary predators): $7{,}300\\,\\text{kJ}$.","Energy supplied to the second trophic level (herbivores) according to the rule $10\\%$: $7300 \\div 0{,}1 = 73\\,000\\,\\text{kJ}$.","Primary production (1-th trophic level) = $73\\,000 \\div 0{,}1 = 730\\,000\\,\\text{kJ}$."]},{"content":"The primary annual production of the ecosystem is $460{,}000$$kJ$. Indicate the amount of energy supplied to the trophic level of the II-order consumer (in kilojoules).[[fill_choice_big-97]]","widgets":{"fill_choice_big-97":{"type":"fill_choice_big","options":["$460$","$46{,}000$","$4{,}600$"],"placeholder":0,"answer":2}},"step":1,"hints":["The rule according to which the transfer of energy between trophic levels occurs with a loss of about $90\\%$, and only ~$10\\%$ is transferred further, was formulated by the American ecologist Raymond Linderman in 1942.","Let's apply Linderman's rule to the problem:<br /><br />Primary production (1-th trophic level) = $460{,}000 \\, \\text{kJ}$.","Energy supplied to the second trophic level (primary consumers) according to the rule $10\\%$: $460{,}000 \\times 0{,}1 = 46{,}000\\,\\text{kJ}$.","3 level (secondary consumers): $46{,}000 \\times 0{,}1 = 4{,}600\\,\\text{kJ}$."]},{"content":"The primary annual production of the ecosystem is $3{,}800{,}000$$kJ$. Indicate the amount of energy supplied to the trophic level of the primary consumer (in kilojoules).[[fill_choice_big-167]]","widgets":{"fill_choice_big-167":{"type":"fill_choice_big","options":["$380{,}000$","$38{,}000$","$3{,}800$"],"placeholder":0,"answer":0}},"step":1,"hints":["The rule according to which the transfer of energy between trophic levels occurs with a loss of about $90\\%$, and only ~$10\\%$ is transferred further, was formulated by the American ecologist Raymond Linderman in 1942.","Let's apply Linderman's rule to the problem:<br /><br />Primary production (1-th trophic level) = $3{,}800{,}000 \\, \\text{kJ}$.","Energy supplied to the second trophic level (herbivores) according to the rule $10\\%$: $3{,}800{,}000 \\times 0{,}1 = 380{,}000\\,\\text{kJ}$."]},{"content":"What is the duration of the systole of the atria of the heart, if it is known that the duration of the entire cardiac cycle is $0,8$$s$, the total diastole is $0,41$$s$, the systole of the ventricles is $0,27$$s$?[[fill_choice_big-280]]","widgets":{"fill_choice_big-280":{"type":"fill_choice_big","options":["$0{,}12$","$0{,}30$","$0{,}22$"],"placeholder":0,"answer":0}},"step":1,"hints":["Calculate using the formula:<br />$$\\text{Systole of the atria} = 0{,}8 — (0{,}27 + 0{,}41) = 0{,}8 — 0{,}68 = 0{,}12\\,\\text{s}$$"]},{"content":"The man's spirogram showed that the tidal volume of his lungs is $700 \\text{cm}^3$, the vital capacity of the lungs is $3900 \\text{cm}^3$, and the expiratory reserve volume is $1500 \\text{cm}^3$. Determine the man's inspiratory reserve volume. [[fill_choice_big-347]]","widgets":{"fill_choice_big-347":{"type":"fill_choice_big","options":["$1700$","$3200$","$700$"],"placeholder":0,"answer":0}},"step":1,"hints":["$$\\text{Vital capacity of the lungs (VC)} = \\text{Tidal volume (TV)} + \\text{Reserve volume inhalation (IRV)} + \\text{Reserve volume exhalation (ERV)}$$","Let's substitute the known values:<br />$$3900 = 700 + \\text{IRV} + 1500$$<br />$$3900 = 2200 + \\text{IRV}$$","Let's find the inspiratory reserve volume:<br />$$\\text{IRV} = 3900 — 2200 = 1700\\,\\text{cm}^3$$"]},{"content":"The woman's spirogram showed that the vital capacity of her lungs is $4200 \\text{cm}^3$, the inspiratory reserve volume is $2000 \\text{cm}^3$, and the tidal volume is $500 \\text{cm}^3$. Determine the woman's expiratory reserve volume.[[fill_choice_big-446]]","widgets":{"fill_choice_big-446":{"type":"fill_choice_big","options":["$1700$","$2500$","$6700$"],"placeholder":0,"answer":0}},"step":1,"hints":["$$\\text{Vital capacity of the lungs (VC)} = \\text{Tidal volume (TV)} + \\text{Reserve volume inhalation (IRV)} + \\text{Reserve volume exhalation (ERV)}$$","Let's substitute the known values:<br />$$4200 = 500 + 2000 + \\text{ERV}$$<br />$$4200 = 2500 + \\text{ERV}$$","Now let’s find the reserve expiratory volume:<br />$$\\text{ERV} = 4200 — 2500 = 1700\\,\\text{cm}^3$$"]},{"content":"The woman's spirogram showed that her expiratory reserve volume was $1600 \\text{cm}^3$, her inspiratory reserve volume was $2200 \\text{cm}^3$, and her tidal volume was $600 \\text{cm}^3$. Determine the vital capacity of the woman's lungs.[[fill_choice_big-572]]","widgets":{"fill_choice_big-572":{"type":"fill_choice_big","options":["$4400$","$2200$","$1200$"],"placeholder":0,"answer":0}},"step":1,"hints":["$$\\text{Vital capacity of the lungs (VC)} = \\text{Tidal volume (TV)} + \\text{Reserve volume inhalation (IRV)} + \\text{Reserve volume exhalation (ERV)}$$","Let's substitute the known values:<br />$$\\text{VC} = 600 + 2200 + 1600 = 4400\\,\\text{cm}^3$$"]},{"content":"What is the duration of the total diastole of the heart, if it is known that the duration of the entire cardiac cycle is $0,8$$s$, ventricular systole - $0,27$$s$, atrial systole - $0,12$$s$?[[fill_choice_big-666]]","widgets":{"fill_choice_big-666":{"type":"fill_choice_big","options":["$0{,}41$","$0{,}07$","$0{,}47$"],"placeholder":0,"answer":0}},"step":1,"hints":["Total diastole is the remaining time of the entire cycle not occupied by systole. Let's calculate using the formula:<br /><br />$$\\text{Total diastole} = 0{,}8 — (0{,}27 + 0{,}12) = 0{,}8 — 0{,}39 = 0{,}41\\,\\text{s}$$"]},{"content":"How many chromosomes does a somatic animal cell have if the gametes contain $38$ chromosomes?[[fill_choice_big-1]]","widgets":{"fill_choice_big-1":{"type":"fill_choice_big","options":["$76$","$38$","$19$"],"placeholder":0,"answer":0}},"step":1,"hints":["If a gamete has 38 chromosomes, then this is a haploid set ($n = 38$).","To find the number of chromosomes in a somatic cell, you need to multiply this number by $2$:<br />$$2n = 2 \\times 38 = 76$$"]},{"content":"How many sex chromosomes does a mammalian somatic cell contain if it contains $60$ chromosomes?[[fill_choice_big-7]]","widgets":{"fill_choice_big-7":{"type":"fill_choice_big","options":["$2$","$1$","$30$"],"placeholder":0,"answer":0}},"step":1,"hints":["In mammals, as in humans, sex chromosomes are part of the general diploid set and form one pair (XX in females, XY in males).","If a somatic cell has $60$ chromosomes, then $2$ chromosomes are the sex chromosomes (this is a $1$ pair)."]},{"content":"How many chromosomes are in a gamete of a bird if its somatic cell contains $32$ chromosomes?[[fill_choice_big-48]]","widgets":{"fill_choice_big-48":{"type":"fill_choice_big","options":["$16$","$8$","$32$"],"placeholder":0,"answer":0}},"step":1,"hints":["Somatic cell is diploid, contains a complete set of chromosomes: $2n=32$.","Gamete is haploid, contains half of the diploid set:<br />$$n = \\frac{2n}{2} = \\frac{32}{2} = 16$$"]},{"content":"How many sex chromosomes are contained in a human somatic cell if the diploid set contains $46$ chromosomes?[[fill_choice_big-76]]","widgets":{"fill_choice_big-76":{"type":"fill_choice_big","options":["$2$","$23$","$16$"],"placeholder":0,"answer":0}},"step":1,"hints":["Diploid set in a somatic cell: $2n=46$.","Of these, $2$ chromosomes are sex chromosomes (XX in women, XY in men), the rest $44$ are autosomes."]},{"content":"How many sex chromosomes does a mammalian somatic cell contain if the diploid set contains $78$ chromosomes?[[fill_choice_big-128]]","widgets":{"fill_choice_big-128":{"type":"fill_choice_big","options":["$2$","$39$","$18$"],"placeholder":0,"answer":0}},"step":1,"hints":["The somatic cell of a mammal is diploid, and it includes a sex pair of chromosomes (XX or XY) - always $2$ chromosomes and the rest - autosomes.","The total number of chromosomes does not affect the number of sex chromosomes - they are always $2$ in a diploid cell of a mammal."]},{"content":"Human sperm contains $23$ chromosomes. How many chromosomes does a human somatic cell have?[[fill_choice_big-173]]","widgets":{"fill_choice_big-173":{"type":"fill_choice_big","options":["$46$","$23$","$92$"],"placeholder":0,"answer":0}},"step":1,"hints":["A sperm is a gamete; it contains a haploid set of chromosomes: $n=23$.","Somatic cell is diploid, contains:<br />$$2n = 2 \\times 23 = 46$$"]},{"content":"A chicken somatic cell contains $78$ chromosomes. How many sex chromosomes does this cell contain?[[fill_choice_big-272]]","widgets":{"fill_choice_big-272":{"type":"fill_choice_big","options":["$2$","$39$","$13$"],"placeholder":0,"answer":0}},"step":1,"hints":["A somatic cell is a diploid cell, and it always contains two sex chromosomes (in a chicken - ZW in a female, ZZ in a male)."]},{"content":"How many sex chromosomes does a somatic cell of a Drosophila fly contain if this cell contains $8$ chromosomes?[[fill_choice_big-353]]","widgets":{"fill_choice_big-353":{"type":"fill_choice_big","options":["$2$","$4$","$8$"],"placeholder":0,"answer":0}},"step":1,"hints":["In the Drosophila fly, the somatic cell contains $8$ chromosomes (this is a diploid set, $2n=8$).","Of these, $6$ chromosomes are autosomes ($3$ pairs), $2$ chromosomes are sex chromosomes ($1$ pair: XX in females, XY in males)."]},{"content":"How many autosomes are contained in a somatic cell of a horse if the diploid set contains $32$ chromosomes?[[fill_choice_big-428]]","widgets":{"fill_choice_big-428":{"type":"fill_choice_big","options":["$2$","$30$","$16$"],"placeholder":0,"answer":1}},"step":1,"hints":["The horse has a diploid set of $2n=32$, of which $2$ chromosomes are sex chromosomes (XX in the female, XY in the male).","From the total number of chromosomes in a diploid cell, we subtract $2$ sex chromosomes - the remaining chromosomes are autosomes.<br />Therefore, the number of autosomes: $32−2=30$."]},{"content":"How many chromosomes does a mammalian somatic cell have if the gamete contains $19$ chromosomes?[[fill_choice_big-513]]","widgets":{"fill_choice_big-513":{"type":"fill_choice_big","options":["$9$","$38$","$19$"],"placeholder":0,"answer":1}},"step":1,"hints":["Gamete is a haploid cell containing $n=19$.","Somatic cell is diploid, contains:<br />$$2n = 2 \\times 19 = 38$$"]}]}